Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2018	Oct. 31, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	ED
Entity Registrant Name	CONSOLIDATED EDISON INC
Entity Central Index Key	0001047862
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		311,418,948
CECONY
Document Information [Line Items]
Entity Registrant Name	CONSOLIDATED EDISON CO OF NEW YORK INC
Entity Central Index Key	0000023632
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Income Statement (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
OPERATING REVENUES
Total operating revenues	$ 3,328	$ 3,211	$ 9,388	$ 9,072
OPERATING EXPENSES
Depreciation and amortization	360	337	1,061	998
Taxes, other than income taxes	597	544	1,707	1,597
TOTAL OPERATING EXPENSES	2,502	2,297	7,381	6,884
Gain on sale of solar electric production project	0	0	0	1
OPERATING INCOME	826	914	2,007	2,189
OTHER INCOME (DEDUCTIONS)
Investment income	39	37	96	90
Other income	7	3	18	12
Allowance for equity funds used during construction	4	3	11	8
Other deductions	(61)	(45)	(154)	(135)
TOTAL OTHER INCOME (DEDUCTIONS)	(11)	(2)	(29)	(25)
INCOME BEFORE INTEREST AND INCOME TAX EXPENSE	815	912	1,978	2,164
INTEREST EXPENSE
Interest on long-term debt	195	183	576	539
Other interest	13	4	28	11
Allowance for borrowed funds used during construction	(3)	(2)	(7)	(5)
NET INTEREST EXPENSE	205	185	597	545
INCOME BEFORE INCOME TAX EXPENSE	610	727	1,381	1,619
INCOME TAX EXPENSE	175	270	330	599
NET INCOME	$ 435	$ 457	$ 1,051	$ 1,020
Net income per common share - basic (dollars per share)	$ 1.40	$ 1.48	$ 3.38	$ 3.33
Net income per common share - diluted (dollars per share)	1.39	1.48	3.37	3.31
DIVIDENDS DECLARED PER COMMON SHARE (dollars per share)	$ 0.72	$ 0.69	$ 2.15	$ 2.07
AVERAGE NUMBER OF SHARES OUTSTANDING-BASIC (shares)	311.1	307.8	310.8	306.2
AVERAGE NUMBER OF SHARES OUTSTANDING—DILUTED (shares)	312.3	309.3	311.9	307.7
Electric
OPERATING REVENUES
Total operating revenues	$ 2,783	$ 2,675	$ 6,611	$ 6,573
Gas
OPERATING REVENUES
Total operating revenues	298	296	1,726	1,593
OPERATING EXPENSES
Operating costs	164	115	736	584
Steam
OPERATING REVENUES
Total operating revenues	64	62	474	448
Non-utility
OPERATING REVENUES
Total operating revenues	183	178	577	458
Power
OPERATING EXPENSES
Operating costs	545	460	1,287	1,253
Fuel
OPERATING EXPENSES
Operating costs	39	30	201	169
Other operations and maintenance
OPERATING EXPENSES
Operating costs	797	811	2,389	2,283
CECONY
OPERATING REVENUES
Total operating revenues	2,899	2,799	8,121	7,948
OPERATING EXPENSES
Depreciation and amortization	322	300	949	891
Taxes, other than income taxes	570	520	1,621	1,523
TOTAL OPERATING EXPENSES	2,135	1,963	6,271	5,949
OPERATING INCOME	764	836	1,850	1,999
OTHER INCOME (DEDUCTIONS)
Investment income	6	2	14	9
Allowance for equity funds used during construction	4	3	10	7
Other deductions	(43)	(41)	(123)	(118)
TOTAL OTHER INCOME (DEDUCTIONS)	(33)	(36)	(99)	(102)
INCOME BEFORE INTEREST AND INCOME TAX EXPENSE	731	800	1,751	1,897
INTEREST EXPENSE
Interest on long-term debt	167	155	492	456
Other interest	10	4	23	11
Allowance for borrowed funds used during construction	(2)	(2)	(7)	(4)
NET INTEREST EXPENSE	175	157	508	463
INCOME BEFORE INCOME TAX EXPENSE	556	643	1,243	1,434
INCOME TAX EXPENSE	125	242	274	551
NET INCOME	431	401	969	883
CECONY \| Electric
OPERATING REVENUES
Total operating revenues	2,571	2,469	6,107	6,079
CECONY \| Gas
OPERATING REVENUES
Total operating revenues	264	268	1,540	1,421
OPERATING EXPENSES
Operating costs	66	58	457	372
CECONY \| Steam
OPERATING REVENUES
Total operating revenues	64	62	474	448
CECONY \| Power
OPERATING EXPENSES
Operating costs	472	400	1,117	1,110
CECONY \| Fuel
OPERATING EXPENSES
Operating costs	39	30	201	169
CECONY \| Other operations and maintenance
OPERATING EXPENSES
Operating costs	$ 666	$ 655	$ 1,926	$ 1,884

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
NET INCOME	$ 435	$ 457	$ 1,051	$ 1,020
OTHER COMPREHENSIVE INCOME, NET OF TAXES
Pension and other postretirement benefit plan liability adjustments, net of taxes	2	1	8	1
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	2	1	8	1
COMPREHENSIVE INCOME	437	458	1,059	1,021
CECONY
NET INCOME	431	401	969	883
OTHER COMPREHENSIVE INCOME, NET OF TAXES
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	0	1	1	1
COMPREHENSIVE INCOME	$ 431	$ 402	$ 970	$ 884

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES
Net income	$ 1,051	$ 1,020
PRINCIPAL NON-CASH CHARGES/(CREDITS) TO INCOME
Depreciation and amortization	1,061	998
Deferred income taxes	308	626
Rate case amortization and accruals	(85)	(93)
Common equity component of allowance for funds used during construction	(11)	(8)
Net derivative gains	5	(4)
Unbilled revenue and net unbilled revenue deferrals	135	37
Gain on sale of solar electric production project	0	(1)
Other non-cash items, net	(44)	(38)
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable – customers	(246)	1
Materials and supplies, including fuel oil and gas in storage	(4)	2
Other receivables and other current assets	(31)	(39)
Taxes receivable	47	33
Prepayments	(487)	(433)
Accounts payable	(8)	(54)
Pensions and retiree benefits obligations, net	264	305
Pensions and retiree benefits contributions	(475)	(462)
Accrued taxes	(60)	(21)
Accrued interest	67	59
Superfund and environmental remediation costs, net	(14)	(9)
Distributions from equity investments	88	87
System benefit charge	74	194
Deferred charges, noncurrent assets and other regulatory assets	(223)	(18)
Deferred credits and other regulatory liabilities	382	(40)
Other current and noncurrent liabilities	(194)	85
NET CASH FLOWS FROM OPERATING ACTIVITIES	1,600	2,227
INVESTING ACTIVITIES
Utility construction expenditures	(2,457)	(2,148)
Cost of removal less salvage	(188)	(185)
Non-utility construction expenditures	(193)	(288)
Proceeds from sale of assets	0	34
Other investing activities	29	32
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,947)	(2,585)
FINANCING ACTIVITIES
Net issuance/(payment) of short-term debt	775	(698)
Issuance of long-term debt	1,905	997
Retirement of long-term debt	(1,319)	(429)
Debt issuance costs	(21)	(12)
Common stock dividends	(631)	(600)
Issuance of common shares - public offering	0	343
Issuance of common shares for stock plans	39	37
NET CASH FLOWS FROM/(USED IN) FINANCING ACTIVITIES	748	(362)
CASH, TEMPORARY CASH INVESTMENTS, AND RESTRICTED CASH:
NET CHANGE FOR THE PERIOD	(599)	(720)
BALANCE AT BEGINNING OF PERIOD	844	830
BALANCE AT END OF PERIOD	245	110
Cash paid/(received) during the period for:
Interest	519	479
Income taxes	(1)	(34)
SUPPLEMENTAL DISCLOSURE OF NON-CASH INFORMATION
Construction expenditures in accounts payable	318	352
Issuance of common shares for dividend reinvestment	36	35
Software licenses acquired but unpaid as of end of period	100	0
CECONY
OPERATING ACTIVITIES
Net income	969	883
PRINCIPAL NON-CASH CHARGES/(CREDITS) TO INCOME
Depreciation and amortization	949	891
Deferred income taxes	346	566
Rate case amortization and accruals	(98)	(107)
Common equity component of allowance for funds used during construction	(10)	(7)
Unbilled revenue and net unbilled revenue deferrals	43	37
Other non-cash items, net	(20)	(51)
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable – customers	(218)	18
Materials and supplies, including fuel oil and gas in storage	(3)	(18)
Other receivables and other current assets	(47)	29
Accounts receivable from affiliated companies	(267)	12
Prepayments	(448)	(398)
Accounts payable	(32)	(20)
Accounts payable to affiliated companies	8	1
Pensions and retiree benefits obligations, net	242	274
Pensions and retiree benefits contributions	(436)	(416)
Accrued taxes	(63)	(18)
Accrued interest	67	61
Superfund and environmental remediation costs, net	(14)	(7)
System benefit charge	70	175
Accrued taxes to affiliated companies	(72)	(119)
Deferred charges, noncurrent assets and other regulatory assets	(158)	(60)
Deferred credits and other regulatory liabilities	376	77
Other current and noncurrent liabilities	(99)	(13)
NET CASH FLOWS FROM OPERATING ACTIVITIES	1,085	1,790
INVESTING ACTIVITIES
Utility construction expenditures	(2,315)	(2,020)
Cost of removal less salvage	(183)	(179)
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,498)	(2,199)
FINANCING ACTIVITIES
Net issuance/(payment) of short-term debt	854	(453)
Issuance of long-term debt	1,640	500
Retirement of long-term debt	(1,236)	0
Debt issuance costs	(18)	(7)
Capital contribution by parent	95	279
Dividend to parent	(635)	(597)
NET CASH FLOWS FROM/(USED IN) FINANCING ACTIVITIES	700	(278)
CASH, TEMPORARY CASH INVESTMENTS, AND RESTRICTED CASH:
NET CHANGE FOR THE PERIOD	(713)	(687)
BALANCE AT BEGINNING OF PERIOD	730	704
BALANCE AT END OF PERIOD	17	17
Cash paid/(received) during the period for:
Interest	424	388
Income taxes	268	96
SUPPLEMENTAL DISCLOSURE OF NON-CASH INFORMATION
Construction expenditures in accounts payable	279	240
Software licenses acquired but unpaid as of end of period	95	0
Electric and Gas Transmission Projects
INVESTING ACTIVITIES
Investments in projects	(123)	(29)
Renewable Electric Production Projects
INVESTING ACTIVITIES
Investments in projects	$ (15)	$ (1)

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and temporary cash investments	$ 199	$ 797
Accounts receivable - customers, less allowance for uncollectible accounts	1,350	1,103
Other receivables, less allowance for uncollectible accounts	263	160
Taxes receivable	29	76
Accrued unbilled revenue	350	598
Fuel oil, gas in storage, materials and supplies, at average cost	338	334
Prepayments	665	178
Regulatory assets	25	67
Restricted cash	46	47
Other current assets	91	177
TOTAL CURRENT ASSETS	3,356	3,537
INVESTMENTS	2,131	2,001
UTILITY PLANT, AT ORIGINAL COST
General	3,205	3,008
TOTAL	44,659	42,731
Less: Accumulated depreciation	9,580	9,063
Net	35,079	33,668
Construction work in progress	1,901	1,605
NET UTILITY PLANT	36,980	35,273
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	1,837	1,776
Construction work in progress	566	551
NET PLANT	39,383	37,600
OTHER NONCURRENT ASSETS
Goodwill	439	428
Intangible assets, less accumulated amortization of $21 and $15 in 2018 and 2017, respectively	132	131
Regulatory assets	3,950	4,266
Other deferred charges and noncurrent assets	153	148
TOTAL OTHER NONCURRENT ASSETS	4,674	4,973
TOTAL ASSETS	49,544	48,111
CURRENT LIABILITIES
Long-term debt due within one year	1,128	1,298
Notes payable	1,352	577
Accounts payable	1,173	1,286
Customer deposits	351	346
Accrued taxes	48	108
Accrued interest	210	143
Accrued wages	109	105
Fair value of derivative liabilities	18	17
Regulatory liabilities	108	101
System benefit charge	609	535
Other current liabilities	295	386
TOTAL CURRENT LIABILITIES	5,401	4,902
NONCURRENT LIABILITIES
Provision for injuries and damages	158	153
Pensions and retiree benefits	804	1,443
Superfund and other environmental costs	720	737
Asset retirement obligations	320	314
Fair value of derivative liabilities	13	38
Deferred income taxes and unamortized investment tax credits	5,834	5,495
Regulatory liabilities	4,624	4,577
Other deferred credits and noncurrent liabilities	292	296
TOTAL NONCURRENT LIABILITIES	12,765	13,053
LONG-TERM DEBT	15,480	14,731
EQUITY
Common shareholders’ equity	15,887	15,418
Noncontrolling interest	11	7
TOTAL EQUITY (See Statement of Equity)	15,898	15,425
TOTAL LIABILITIES AND EQUITY	49,544	48,111
Electric
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	30,077	28,994
Gas
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	8,877	8,256
Steam
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	2,500	2,473
CECONY
CURRENT ASSETS
Cash and temporary cash investments	17	730
Accounts receivable - customers, less allowance for uncollectible accounts	1,228	1,009
Other receivables, less allowance for uncollectible accounts	167	92
Taxes receivable	5	19
Accrued unbilled revenue	298	454
Accounts receivable from affiliated companies	331	64
Fuel oil, gas in storage, materials and supplies, at average cost	290	287
Prepayments	556	108
Regulatory assets	19	62
Other current assets	59	84
TOTAL CURRENT ASSETS	2,970	2,909
INVESTMENTS	415	383
UTILITY PLANT, AT ORIGINAL COST
General	2,932	2,753
TOTAL	41,823	40,024
Less: Accumulated depreciation	8,801	8,321
Net	33,022	31,703
Construction work in progress	1,803	1,502
NET UTILITY PLANT	34,825	33,205
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	4	4
NET PLANT	34,829	33,209
OTHER NONCURRENT ASSETS
Regulatory assets	3,576	3,863
Other deferred charges and noncurrent assets	69	87
TOTAL OTHER NONCURRENT ASSETS	3,645	3,950
TOTAL ASSETS	41,859	40,451
CURRENT LIABILITIES
Long-term debt due within one year	1,075	1,200
Notes payable	1,004	150
Accounts payable	953	1,057
Accounts payable to affiliated companies	18	10
Customer deposits	339	334
Accrued taxes	39	102
Accrued taxes to affiliated companies	0	72
Accrued interest	180	113
Accrued wages	99	95
Fair value of derivative liabilities	4	12
Regulatory liabilities	85	65
System benefit charge	553	483
Other current liabilities	234	245
TOTAL CURRENT LIABILITIES	4,583	3,938
NONCURRENT LIABILITIES
Provision for injuries and damages	153	147
Pensions and retiree benefits	547	1,140
Superfund and other environmental costs	626	637
Asset retirement obligations	296	287
Fair value of derivative liabilities	9	31
Deferred income taxes and unamortized investment tax credits	5,707	5,306
Regulatory liabilities	4,242	4,219
Other deferred credits and noncurrent liabilities	240	242
TOTAL NONCURRENT LIABILITIES	11,820	12,009
LONG-TERM DEBT	12,587	12,065
EQUITY
Common shareholders’ equity	12,869	12,439
TOTAL LIABILITIES AND EQUITY	41,859	40,451
CECONY \| Electric
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	28,308	27,299
CECONY \| Gas
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	8,083	7,499
CECONY \| Steam
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	$ 2,500	$ 2,473

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts receivable - customers, allowance for uncollectible accounts	$ 62	$ 63
Other receivables, allowance for uncollectible accounts	6	8
Non-utility property, accumulated depreciation	248	201
Intangible assets, accumulated amortization	21	15
CECONY
Accounts receivable - customers, allowance for uncollectible accounts	57	58
Other receivables, allowance for uncollectible accounts	5	7
Non-utility property, accumulated depreciation	$ 25	$ 25

Consolidated Statement of Equity/Shareholder's Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Capital Stock Expense	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interest	CECONY	CECONY Common Stock	CECONY Additional Paid-In Capital	CECONY Retained Earnings	CECONY Repurchased Con Edison Stock	CECONY Capital Stock Expense	CECONY Accumulated Other Comprehensive Income/(Loss)
Beginning Balance at Dec. 31, 2016							$ (27)								$ (7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 1,020								$ 883
Other comprehensive income	1								1
Ending Balance at Sep. 30, 2017							(26)								(6)
Beginning Balance at Jun. 30, 2017							(27)								(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	457								401
Other comprehensive income	1								1
Noncontrolling interest	4
Ending Balance at Sep. 30, 2017							(26)								(6)
Beginning Balance (in shares) at Dec. 31, 2017		310			23					235
Beginning Balance at Dec. 31, 2017	15,425	$ 34	$ 6,298	$ 10,235	$ (1,038)	$ (85)	(26)	$ 7							(6)
Beginning Balance at Dec. 31, 2017	15,418								12,439	$ 589	$ 4,649	$ 8,231	$ (962)	$ (62)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,051			1,051					969			969
Common stock dividends	(667)			(667)					(635)			(635)
Issuance of common shares for stock plans (in shares)		1
Issuance of common shares for stock plans	77		77
Capital contribution by parent									95		95
Other comprehensive income	8						8		1						1
Noncontrolling interest								4
Ending Balance (in shares) at Sep. 30, 2018		311			23					235
Ending Balance at Sep. 30, 2018	15,898	$ 34	6,375	10,619	$ (1,038)	(85)	(18)	11							(5)
Ending Balance at Sep. 30, 2018	15,887								12,869	$ 589	4,744	8,565	(962)	(62)	(5)
Beginning Balance at Jun. 30, 2018							(20)								(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	435								431
Other comprehensive income	2								0
Ending Balance (in shares) at Sep. 30, 2018		311			23					235
Ending Balance at Sep. 30, 2018	15,898	$ 34	$ 6,375	$ 10,619	$ (1,038)	$ (85)	$ (18)	$ 11							(5)
Ending Balance at Sep. 30, 2018	$ 15,887								$ 12,869	$ 589	$ 4,744	$ 8,565	$ (962)	$ (62)	$ (5)

General	9 Months Ended
General	Sep. 30, 2018
Accounting Policies [Abstract]
General	General These combined notes accompany and form an integral part of the separate consolidated financial statements of each of the two separate registrants: Consolidated Edison, Inc. and its subsidiaries (Con Edison) and Consolidated Edison Company of New York, Inc. and its subsidiaries (CECONY). CECONY is a subsidiary of Con Edison and as such its financial condition and results of operations and cash flows, which are presented separately in the CECONY consolidated financial statements, are also consolidated, along with those of Orange and Rockland Utilities, Inc. (O&R), Con Edison Clean Energy Businesses, Inc. (together with its subsidiaries, the Clean Energy Businesses) and Con Edison Transmission, Inc. (together with its subsidiaries, Con Edison Transmission) in Con Edison’s consolidated financial statements. The term “Utilities” is used in these notes to refer to CECONY and O&R. As used in these notes, the term “Companies” refers to Con Edison and CECONY and, except as otherwise noted, the information in these combined notes relates to each of the Companies. However, CECONY makes no representation as to information relating to Con Edison or the subsidiaries of Con Edison other than itself. The separate interim consolidated financial statements of each of the Companies are unaudited but, in the opinion of their respective managements, reflect all adjustments (which include only normally recurring adjustments) necessary for a fair presentation of the results for the interim periods presented. The Companies’ separate interim consolidated financial statements should be read together with their separate audited financial statements (including the combined notes thereto) included in Item 8 of their combined Annual Report on Form 10-K for the year ended December 31, 2017 and their separate unaudited financial statements (including the combined notes thereto) included in Part 1, Item 1 of their combined Quarterly Report on Form 10-Q for the quarterly periods ended March 31, 2018 and June 30, 2018. Certain prior period amounts have been reclassified to conform to the current period presentation. Con Edison has two regulated utility subsidiaries: CECONY and O&R. CECONY provides electric service and gas service in New York City and Westchester County. The company also provides steam service in parts of Manhattan. O&R, along with its regulated utility subsidiary, provides electric service in southeastern New York and northern New Jersey and gas service in southeastern New York. Con Edison Clean Energy Businesses, Inc. has three subsidiaries: Consolidated Edison Development, Inc. (Con Edison Development), a company that develops, owns and operates renewable and energy infrastructure projects; Consolidated Edison Energy, Inc. (Con Edison Energy), a company that provides energy-related products and services to wholesale customers; and Consolidated Edison Solutions, Inc. (Con Edison Solutions), a company that provides energy-related products and services to retail customers. Con Edison Transmission, Inc. invests in electric transmission facilities through its subsidiary, Consolidated Edison Transmission, LLC (CET Electric), and invests in gas pipeline and storage facilities through its subsidiary Con Edison Gas Pipeline and Storage, LLC (CET Gas).

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Revenues

Adoption of New Standard

On January 1, 2018, the Companies adopted Accounting Standards Codification (ASC) Topic 606, “Revenue from Contracts with Customers,” using the modified retrospective method applied to those contracts that were not completed. No charge to retained earnings for cumulative impact was required as a result of the Companies’ adoption of Topic 606.

Revenue Recognition

The following table presents, for the three and nine months ended September 30, 2018, revenue from contracts with customers as defined in Topic 606, as well as additional revenue from sources other than contracts with customers, disaggregated by major source.



	For the Three Months Ended September 30, 2018					For the Nine Months Ended September 30, 2018
(Millions of Dollars)	Revenues from contracts with customers		Other revenues (a)		Total operating revenues	Revenues from contracts with customers		Other revenues (a)	Total operating revenues
CECONY
Electric	$2,631		$(60)		$2,571	$6,106		$1	$6,107
Gas	264		—		264	1,516		24	1,540
Steam	64		—		64	467		7	474
Total CECONY	$2,959		$(60)		$2,899	$8,089		$32	$8,121
O&R
Electric	215		(3)		212	508		(3)	505
Gas	31		3		34	179		7	186
Total O&R	$246			$—	$246	$687		$4	$691
Clean Energy Businesses
Renewables	68	(b)	—		68	273	(b)	—	273
Energy services	24		—		24	65		—	65
Other	—		89		89	—		235	235
Total Clean Energy Businesses	$92		$89		$181	$338		$235	$573
Con Edison Transmission	1		—		1	3		—	3
Other (c)	—		1		1	—		—	—
Total Con Edison	$3,298		$30		$3,328	$9,117		$271	$9,388

(a) For the Utilities, this includes revenue from alternative revenue programs, such as the revenue decoupling mechanisms under their New York electric and gas rate plans.For the Clean Energy Businesses, this includes revenue from wholesale services.

(b) Included within the total for Renewables revenue at the Clean Energy Businesses is $3 million and $100 million for the three and nine months ended September 30, 2018, respectively, of revenue related to engineering, procurement and construction services.


(c)	Parent company and consolidation adjustments.

The Utilities have the obligation to deliver electricity, gas and steam energy to their customers. The Utilities recognize revenues as this performance obligation is satisfied over time as the Utilities deliver, and the customers simultaneously receive and consume, the energy. The amount of revenues recognized reflects the consideration the Utilities expect to receive in exchange for delivering the energy. Under their tariffs, the transaction price for full-service customers includes the Utilities’ energy cost and for all customers includes delivery charges determined based on customer class and in accordance with established tariffs and guidelines of the New York State Public Service Commission (NYSPSC) or the New Jersey Board of Public Utilities (NJBPU), as applicable. Accordingly, there is no unsatisfied performance obligation associated with these customers. The transaction price is applied to the Utilities’ revenue generating activities through the customer billing process. Because energy is delivered over time, the Utilities use output methods that recognize revenue based on direct measurement of the value transferred, such as units delivered, which provides an accurate measure of value for the energy delivered. The Utilities accrue revenues at the end of each month for estimated energy delivered but not yet billed to customers. The Utilities defer over a 12-month period net interruptible gas revenues, other than those authorized by the NYSPSC to be retained by the Utilities, for refund to firm gas sales and transportation customers.

Con Edison Development recognizes revenue for the sale of energy from renewable electric production projects as energy is generated and billed to counterparties. Con Edison Development accrues revenues at the end of each month for energy generated but not yet billed to counterparties. Con Edison Energy recognizes revenue as energy is delivered and services are provided for managing energy supply assets leased from others and managing the dispatch, fuel requirements and risk management activities for generating plants and merchant transmission in the northeastern United States. Con Edison Solutions recognizes revenue for providing energy-efficiency services to government and commercial customers, and Con Edison Development recognizes revenue for engineering, procurement and construction services, under the percentage-of-completion method of revenue recognition.

Sales and profits on each percentage-of-completion contract are recorded each month based on the ratio of actual cumulative costs incurred to the total estimated costs at completion of the contract, multiplied by the total estimated contract revenue, less cumulative revenues recognized in prior periods (the ‘‘cost-to-cost’’ method). The impact of revisions of contract estimates, which may result from contract modifications, performance or other reasons, are recognized on a cumulative catch-up basis in the period in which the revisions are made.



(Millions of Dollars)	Unbilled contract revenue (a)	Unearned revenue (b)
Beginning balance as of January 1, 2018	$58	$87
Additions (c)	111	34
Subtractions (c)	138	105	(d)
Ending balance as of September 30, 2018	$31	$16

(a)

Unbilled contract revenue represents accumulated incurred costs and earned profits on contracts (revenue arrangements), which have been recorded as revenue, but have not yet been billed to customers, and which represent contract assets as defined in Topic 606. Substantially all accrued unbilled contract revenue is expected to be collected within one year. Unbilled contract revenue arises from the cost-to-cost method of revenue recognition. Unbilled contract revenue from fixed-price type contracts is converted to billed receivables when amounts are invoiced to customers according to contractual billing terms, which generally occur when deliveries or other performance milestones are completed.


(b)	Unearned revenue represents a liability for billings to customers in excess of earned revenue, which are contract liabilities as defined in Topic 606.


(c)	Additions for unbilled contract revenue and subtractions for unearned revenue represent additional revenue earned. Additions for unearned revenue and subtractions for unbilled contract revenue represent billings. Activity also includes appropriate balance sheet classification for the period.


(d)	Of the $105 million in subtractions from unearned revenue, $50 million was included in the balance as of December 31, 2017.

As of September 30, 2018, the aggregate amount of the remaining fixed performance obligations is $124 million, of which $87 million will be recognized within the next two years, and the remaining $37 million will be recognized pursuant to long-term service and maintenance agreements.

Revenues are recorded as energy is delivered, generated or services are provided and billed to customers, except for services under percentage-of-completion contracts. Amounts billed are recorded in accounts receivable - customers, with payment generally due the following month. Con Edison’s and the Utilities’ accounts receivable - customers balance also reflects the Utilities’ purchase of receivables from energy service companies to support retail choice programs. Accrued revenues not yet billed to customers are recorded as accrued unbilled revenues.

Utility Plant

At September 30, 2018, utility plant of Con Edison and CECONY included $102 million and $97 million, respectively, related to a May 2018 acquisition of software licenses. The software licenses asset is being amortized over a period of 15 years, and the estimated aggregate annual amortization expense for Con Edison and CECONY is $7 million. At September 30, 2018, the accumulated amortization for Con Edison and CECONY was $2 million and $1 million, respectively.

Earnings Per Common Share

Con Edison presents basic and diluted earnings per share (EPS) on the face of its consolidated income statement. Basic EPS is calculated by dividing earnings available to common shareholders (“Net income” on Con Edison’s consolidated income statement) by the weighted average number of Con Edison common shares outstanding during the period. In the calculation of diluted EPS, weighted average shares outstanding are increased for additional shares that would be outstanding if potentially dilutive securities were converted to common stock.

Potentially dilutive securities for Con Edison consist of restricted stock units and deferred stock units for which the average market price of the common shares for the period was greater than the exercise price.

For the three and nine months ended September 30, 2018 and 2017, basic and diluted EPS for Con Edison are calculated as follows:



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(Millions of Dollars, except per share amounts/Shares in Millions)	2018	2017	2018	2017
Net income	$435	$457	$1,051	$1,020
Weighted average common shares outstanding – basic	311.1	307.8	310.8	306.2
Add: Incremental shares attributable to effect of potentially dilutive securities	1.2	1.5	1.1	1.5
Adjusted weighted average common shares outstanding – diluted	312.3	309.3	311.9	307.7
Net Income per common share – basic	$1.40	$1.48	$3.38	$3.33
Net Income per common share – diluted	$1.39	$1.48	$3.37	$3.31

The computation of diluted EPS for the three and nine months ended September 30, 2018 excludes immaterial amounts of performance share awards that were not included because of their anti-dilutive effect.

Changes in Accumulated Other Comprehensive Income/(Loss) by Component

For the three and nine months ended September 30, 2018 and 2017, changes to accumulated other comprehensive income/(loss) (OCI) for Con Edison and CECONY are as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Beginning balance, accumulated OCI, net of taxes (a)	$(20)	$(27)	$(5)	$(7)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(1) for Con Edison in 2018 and 2017 (a)(b)	2	1	—	1
Current period OCI, net of taxes	2	1	—	1
Ending balance, accumulated OCI, net of taxes	$(18)	$(26)	$(5)	$(6)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Beginning balance, accumulated OCI, net of taxes (a)	$(26)	$(27)	$(6)	$(7)
OCI before reclassifications, net of tax of $(1) and $1 for Con Edison in 2018 and 2017, respectively	3	(2)	—	—
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(2) for Con Edison in 2018 and 2017 (a)(b)	5	3	1	1
Current period OCI, net of taxes	8	1	1	1
Ending balance, accumulated OCI, net of taxes	$(18)	$(26)	$(5)	$(6)


(a)	Tax reclassified from accumulated OCI is reported in the income tax expense line item of the consolidated income statement.


(b)	For the portion of unrecognized pension and other postretirement benefit costs relating to the Utilities, costs are recorded into, and amortized out of, regulatory assets instead of OCI. The net actuarial losses and prior service costs recognized during the period are included in the computation of total periodic pension and other postretirement benefit cost. See Notes E and F.

Reconciliation of Cash, Temporary Cash Investments and Restricted Cash

On January 1, 2018, the Companies adopted Accounting Standard Update (ASU) 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash," which they applied retrospectively for each prior period presented. Pursuant to ASU 2016-18, cash, temporary cash investments and restricted cash are presented on a combined basis in the Companies’ consolidated statements of cash flows. At September 30, 2018 and 2017, cash, temporary cash investments and restricted cash for Con Edison and CECONY are as follows:



	At September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Cash and temporary cash investments	$199	$69	$17	$17
Restricted cash (a)	46	41	—	—
Total cash, temporary cash investments and restricted cash	$245	$110	$17	$17

(a)

Restricted cash is comprised of O&R's New Jersey utility subsidiary, Rockland Electric Company transition bond charge collections, net of principal, interest, trustee and service fees ($2 million at September 30, 2018 and 2017) that are restricted until the bonds mature in 2019, and the Clean Energy Businesses' cash collateral held for project finance agreements ($44 million and $39 million at September 30, 2018 and 2017, respectively) that are restricted until varying maturity dates. For these projects, such funds are restricted to being used for normal operating expenses and capital expenditures, debt service, and required reserves.

Regulatory Matters

9 Months Ended

Sep. 30, 2018

Regulated Operations [Abstract]

Regulatory Matters

Rate Plans

O&R New York – Electric

In May 2018, in O&R's electric rate proceeding, the NYSPSC staff recommended a $10.6 million increase in O&R's electric rates (reflecting an authorized return on common equity of 8.6 percent). In June 2018, O&R filed an update to its requested rate increase, changing its request to a $30.4 million increase (reflecting an authorized return on common equity of 9.75 percent).

O&R New York – Gas

In May 2018, in O&R's gas rate proceeding, the NYSPSC staff recommended a $6.7 million decrease in O&R's gas rates (reflecting an authorized return on common equity of 8.6 percent). In June 2018, O&R filed an update to its requested rate increase, changing its request to a $0.5 million decrease (reflecting an authorized return on common equity of 9.75 percent).

Other Regulatory Matters

In August and November 2017, the NYSPSC issued orders in its proceeding investigating an April 21, 2017 Metropolitan Transportation Authority (MTA) subway power outage. The orders indicated that the investigation determined that the outage was caused by a failure of CECONY’s electricity supply to a subway station, which led to a loss of the subway signals, and that one of the secondary services to the MTA facility had been improperly rerouted and was not properly documented by the company. The orders also indicated that the loss of power to the subway station affected multiple subway lines and caused widespread delays across the subway system. Pursuant to the orders, the company is required to take certain actions, including inspecting, repairing and installing certain electrical equipment that serves the subway system, analyzing power supply and power quality events affecting the MTA’s signaling services, and filing monthly reports with the NYSPSC on all of the company's activities related to the subway system. Through September 30, 2018, the company incurred costs related to this matter of $219 million. Included in this amount is $30 million in capital and operating and maintenance costs reflected in the company's electric rate plan and $189 million deferred as a regulatory asset pursuant to the rate plan. The company, which plans to complete the required actions in 2018, expects to incur costs related to this matter during the remainder of 2018 of $51 million, which is expected to be deferred as a regulatory asset pursuant to the rate plan.

In December 2017, the NYSPSC issued an order initiating a proceeding to study the potential effects of the federal Tax Cuts and Jobs Act of 2017 (TCJA) on income tax expense and liabilities of New York State utilities and the regulatory treatment to preserve the resulting benefits for customers. Upon enactment of the TCJA in December 2017, CECONY and O&R re-measured their deferred tax assets and liabilities and accrued net regulatory liabilities for future income taxes of $3,513 million and $161 million, respectively. In September 2018, CECONY and O&R accrued additional net regulatory liabilities for future income tax of $51 million and $7 million, respectively (see Note I). Under the rate normalization requirements continued by the TCJA, the "protected" portion of their net regulatory liabilities related to certain accelerated tax depreciation benefits ($2,593 million and $133 million, respectively) is to be amortized over the remaining lives of the related assets. The remainder of the net regulatory liabilities, or "unprotected" portion, ($971 million and $35 million, respectively) is to be amortized as determined by the NYSPSC.

In August 2018, the NYSPSC ordered CECONY to begin on January 1, 2019 to credit the company's electric and gas customers, and to begin on October 1, 2018 to credit its steam customers, with the net benefits of the TCJA as measured based on amounts reflected in its rate plans prior to the enactment of the TCJA. The net benefits include the revenue requirement impact of the reduction in the corporate federal income tax rate to 21 percent, the elimination for utilities of bonus depreciation and the amortization of excess deferred federal income taxes.

CECONY estimates that its credit of net benefits to its electric, gas and steam customers in 2019 will amount to $247 million, $102 million and $25 million, respectively (and that its credit to its steam customers in the fourth quarter of 2018 will be $6 million). CECONY’s net benefits prior to January 1, 2019 allocable to the company’s electric customers (estimated $304 million) are to be deferred and addressed in its next electric rate proceeding. CECONY’s net benefits prior to January 1, 2019 allocable to the company’s gas customers (estimated $82 million) and net benefits prior to October 1, 2018 allocable to the company’s steam customers ($15 million) are to be amortized over a three-year period. CECONY’s net regulatory liability for future income taxes, including both the protected and unprotected portions, allocable to the company’s electric customers ($2,514 million) is to continue to be deferred until its next electric rate proceeding and the amounts allocable to its gas and steam customers ($808 million and $190 million, respectively) are to be amortized over the remaining lives of the related assets (with the amortization period for the unprotected portion subject to review in its next gas and steam rate proceedings). O&R, in its ongoing rate proceedings (see “Rate Plans,” above), intends to reflect its TCJA net benefits in its electric and gas rates beginning as of January 1, 2019, to amortize its net benefits prior to January 1, 2019 (estimated $22 million) over a three-year period and to amortize the protected portion of its net regulatory liability for future income taxes over the remaining lives of the related assets and the unprotected portion over a fifteen-year period.

For the nine months ended September 30, 2018, the Utilities deferred as regulatory liabilities estimated net benefits of the TCJA of $325 million, which represented approximately three quarters of their estimated annual net benefits.

In January 2018, the NYSPSC issued an order initiating a focused operations audit of the income tax accounting of certain utilities, including CECONY and O&R.

In January 2018, the NJBPU issued an order initiating a proceeding to consider the TCJA. In June 2018, the NJBPU made permanent its previously approved $2.9 million interim decrease in Rockland Electric Company's (RECO) electric base rates, effective April 1, 2018, and ordered RECO to pay to its customers in July 2018 its approximately $1 million of net benefits of the TCJA for the three-month period ended March 31, 2018 and to begin in July 2018 to refund to its customers the unprotected portion of its net regulatory liability for future income taxes over a three-year period. Also in March 2018, the Federal Energy Regulatory Commission (FERC) issued an order directing RECO to propose revisions to its transmission revenue requirement to reflect the TCJA. RECO’s net regulatory liability for future income taxes resulting from its re-measurement of its deferred tax asset and liabilities is $28 million (including $16 million subject to the normalization requirements continued by the TCJA).

In March 2018, Winter Storms Riley and Quinn caused damage to the Utilities’ electric distribution systems and interrupted service to approximately 209,000 CECONY customers, 93,000 O&R customers and 44,000 RECO customers. Through September 30, 2018, CECONY's costs related to March 2018 storms, including Riley and Quinn, amounted to $125 million, including operation and maintenance expenses reflected in its electric rate plan ($16 million), operation and maintenance expenses charged against a storm reserve pursuant to its electric rate plan ($76 million), capital expenditures ($27 million) and removal costs ($6 million). O&R and RECO had storm-related costs of $44 million and $17 million, respectively, most of which were deferred as regulatory assets pursuant to their electric rate plans. Recovery of CECONY and O&R storm-related costs is subject to review by the NYSPSC, and recovery of RECO storm-related costs is subject to review by the NJBPU. The NYSPSC is investigating the preparation and response to the storms by CECONY, O&R, and other New York electric utilities, including all aspects of their emergency response plans, and may penalize them. In July 2018, the NJBPU adopted NJBPU staff's recommendations to increase requirements for New Jersey utilities, including RECO, relating to pre-storm preparations, restoration of service and communications and outreach. The Companies are unable to estimate the amount or range of their possible loss in connection with the storms.

In May 2018, FERC denied a complaint the NJBPU filed with FERC seeking the re-allocation to CECONY of certain PJM Interconnection LLC (PJM) transmission costs that had been allocated to the company prior to April 2017 when transmission service provided to the company pursuant to the PJM open access transmission tariff terminated. The transmission service terminated because the company did not exercise its option to continue the service following a series of requests PJM had submitted to FERC that substantially increased the charges for the transmission service. CECONY challenged each of these requests. FERC rejected all but one of CECONY’s protests. In June 2015 and May 2016, CECONY filed appeals of certain FERC decisions with the U.S. Court of Appeals. In July 2018, FERC established a settlement proceeding relating to the allocation of PJM transmission costs. Under CECONY’s electric rate plan, unless and until changed by the NYSPSC, the company will recover all charges incurred associated with the transmission service.

In July 2018, the NYSPSC commenced an investigation into the rupture of a CECONY steam main (see Note H).

Regulatory Assets and Liabilities

Regulatory assets and liabilities at September 30, 2018 and December 31, 2017 were comprised of the following items:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Regulatory assets
Unrecognized pension and other postretirement costs	$2,001	$2,526	$1,881	$2,376
Environmental remediation costs	754	793	653	677
Revenue taxes	287	260	274	248
MTA power reliability deferral	189	50	189	50
Property tax reconciliation	85	51	68	25
Deferred storm costs	80	38	—	—
Pension and other postretirement benefits deferrals	73	79	56	58
Municipal infrastructure support costs	73	56	73	56
Recoverable energy costs	62	60	57	52
Unamortized loss on reacquired debt	37	37	36	35
Meadowlands heater odorization project	36	18	36	18
Brooklyn Queens demand management program	30	37	30	37
Preferred stock redemption	23	24	23	24
Deferred derivative losses	21	44	16	37
Gate station upgrade project	19	13	19	13
Recoverable REV demonstration project costs	18	19	16	17
Indian Point Energy Center program costs	15	29	15	29
Workers’ compensation	6	10	6	10
O&R transition bond charges	3	9	—	—
Other	138	113	128	101
Regulatory assets – noncurrent	3,950	4,266	3,576	3,863
Deferred derivative losses	19	40	14	37
Recoverable energy costs	6	27	5	25
Regulatory assets – current	25	67	19	62
Total Regulatory Assets	$3,975	$4,333	$3,595	$3,925
Regulatory liabilities
Future income tax	$2,547	$2,545	$2,389	$2,390
Allowance for cost of removal less salvage	878	846	745	719
TCJA net benefits*	325	—	304	—
Energy efficiency portfolio standard unencumbered funds	127	127	122	122
Pension and other postretirement benefit deferrals	120	207	97	181
Net unbilled revenue deferrals	86	183	86	183
Unrecognized other postretirement costs	78	92	78	92
Property tax reconciliation	57	107	57	107
Property tax refunds	45	44	45	44
Settlement of prudence proceeding	44	66	44	66
Earnings sharing - electric, gas and steam	25	29	16	19
Carrying charges on repair allowance and bonus depreciation	24	43	24	42
New York State income tax rate change	21	36	22	35
Settlement of gas proceedings	16	27	16	27
Base rate change deferrals	13	21	13	21
Variable-rate tax-exempt debt – cost rate reconciliation	7	30	6	26
Net utility plant reconciliations	7	12	4	8
Other	204	162	174	137
Regulatory liabilities – noncurrent	4,624	4,577	4,242	4,219
Revenue decoupling mechanism	56	29	55	21
Refundable energy costs	32	41	12	16
Deferred derivative gains	20	31	18	28
Regulatory liabilities – current	108	101	85	65
Total Regulatory Liabilities	$4,732	$4,678	$4,327	$4,284

* See "Other Regulatory Matters," above.

Capitalization

9 Months Ended

Sep. 30, 2018

Debt Disclosure [Abstract]

Capitalization

In April 2018, CECONY redeemed at maturity $600 million of 5.85 percent 10-year debentures. In May 2018, CECONY issued $300 million aggregate principal amount of 3.80 percent debentures, due 2028, and $700 million aggregate principal amount of 4.50 percent debentures, due 2058. In June 2018, CECONY issued $640 million of floating rate debentures, due 2021, and in July and August 2018, CECONY redeemed $636 million of its tax-exempt debt for which the interest rates were to be determined pursuant to periodic auctions. In August 2018, O&R issued $125 million aggregate principal amount of 4.35 percent debentures, due 2048, and agreed to issue an additional $25 million aggregate principal amount of debentures in December 2018. In September 2018, O&R redeemed at maturity $50 million of 6.15 percent 10-year debentures. In September 2018, a Con Edison Development subsidiary issued $140 million aggregate principal amount of 4.41 percent Senior Notes, due 2028, secured by five of the company's wind electric production projects.

The carrying amounts and fair values of long-term debt at September 30, 2018 and December 31, 2017 were:



(Millions of Dollars)	2018		2017
Long-Term Debt (including current portion) (a)	Carrying Amount	Fair Value	Carrying Amount	Fair Value
Con Edison	$16,608	$17,369	$16,029	$18,147
CECONY	$13,662	$14,333	$13,265	$15,163


(a)	Amounts shown are net of unamortized debt expense and unamortized debt discount of $149 million and $128 million for Con Edison and CECONY, respectively, as of September 30, 2018 and $142 million and $121 million for Con Edison and CECONY, respectively, as of December 31, 2017.

The fair values of the Companies' long-term debt have been estimated primarily using available market information and at September 30, 2018 are classified as Level 2 (see Note L).

Pension Benefits

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Pension Benefits

Total Periodic Benefit Cost

The components of the Companies’ total periodic benefit cost for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$72	$66	$68	$61
Interest cost on projected benefit obligation	140	148	131	139
Expected return on plan assets	(258)	(243)	(245)	(229)
Recognition of net actuarial loss	172	149	163	141
Recognition of prior service cost/(credit)	(4)	(4)	(5)	(5)
TOTAL PERIODIC BENEFIT COST	$122	$116	$112	$107
Cost capitalized	(32)	(40)	(30)	(37)
Reconciliation to rate level	(22)	(14)	(24)	(16)
Total expense recognized	$68	$62	$58	$54



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$218	$197	$204	$184
Interest cost on projected benefit obligation	420	444	394	416
Expected return on plan assets	(775)	(726)	(734)	(689)
Recognition of net actuarial loss	516	446	488	423
Recognition of prior service cost/(credit)	(13)	(13)	(15)	(14)
TOTAL PERIODIC BENEFIT COST	$366	$348	$337	$320
Cost capitalized	(94)	(134)	(89)	(125)
Reconciliation to rate level	(68)	(28)	(74)	(32)
Total expense recognized	$204	$186	$174	$163

In March 2017, the FASB issued amendments to the guidance for retirement benefits through ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” The Companies adopted ASU 2017-07 beginning on January 1, 2018. The guidance requires that components of net periodic benefit cost other than service cost be presented outside of operating income on consolidated income statements, and that only the service cost component is eligible for capitalization. Accordingly, the service cost components are included in the line "Other operations and maintenance" and the non-service cost components are included in the line “Other deductions” in the Companies' consolidated income statements. As permitted by a practical expedient under ASU 2017-07, the Companies applied the presentation requirements retrospectively for both pension and other postretirement benefit costs using amounts disclosed in prior-period financial statements as appropriate estimates.

Expected Contributions

Based on estimates as of September 30, 2018, the Companies expect to make contributions to the pension plans during 2018 of $472 million (of which $433 million is to be contributed by CECONY). The Companies’ policy is to fund the total periodic benefit cost of the qualified plan to the extent tax deductible and to also contribute to the non-qualified supplemental plans. During the first nine months of 2018, the Companies contributed $469 million to the pension plans (of which $431 million was contributed by CECONY). CECONY also contributed $17 million to the external trust for its non-qualified supplemental plan.

Other Postretirement Benefits

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Other Postretirement Benefits

Total Periodic Benefit Cost

The components of the Companies’ total periodic other postretirement benefit cost/(credit) for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$5	$5	$3	$3
Interest cost on accumulated other postretirement benefit obligation	11	11	9	9
Expected return on plan assets	(18)	(17)	(16)	(15)
Recognition of net actuarial loss/(gain)	2	1	1	—
Recognition of prior service cost/(credit)	(2)	(5)	(1)	(3)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(2)	$(5)	$(4)	$(6)
Cost capitalized	(2)	2	(1)	2
Reconciliation to rate level	2	(1)	2	—
Total expense/(credit) recognized	$(2)	$(4)	$(3)	$(4)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$15	$15	$10	$10
Interest cost on accumulated other postretirement benefit obligation	32	34	26	28
Expected return on plan assets	(55)	(52)	(47)	(45)
Recognition of net actuarial loss/(gain)	6	2	2	(2)
Recognition of prior service cost/(credit)	(5)	(13)	(2)	(9)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(7)	$(14)	$(11)	$(18)
Cost capitalized	(6)	6	(4)	7
Reconciliation to rate level	6	(3)	7	(1)
Total expense/(credit) recognized	$(7)	$(11)	$(8)	$(12)

For information about the adoption of ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” see Note E.

Contributions

During the first nine months of 2018, the Companies contributed $6 million, substantially all of which was contributed by CECONY, to the other postretirement benefit plans. The Companies' policy is to fund the total periodic benefit cost of the plans to the extent tax deductible.

Environmental Matters

9 Months Ended

Sep. 30, 2018

Environmental Remediation Obligations [Abstract]

Environmental Matters

Superfund Sites

Hazardous substances, such as asbestos, polychlorinated biphenyls (PCBs) and coal tar, have been used or generated in the course of operations of the Utilities and their predecessors and are present at sites and in facilities and equipment they currently or previously owned, including sites at which gas was manufactured or stored.

The Federal Comprehensive Environmental Response, Compensation and Liability Act of 1980 and similar state statutes (Superfund) impose joint and several liability, regardless of fault, upon generators of hazardous substances for investigation and remediation costs (which include costs of demolition, removal, disposal, storage, replacement, containment and monitoring) and natural resource damages. Liability under these laws can be material and may be imposed for contamination from past acts, even though such past acts may have been lawful at the time they occurred. The sites at which the Utilities have been asserted to have liability under these laws, including their manufactured gas plant sites and any neighboring areas to which contamination may have migrated, are referred to herein as “Superfund Sites.”

For Superfund Sites where there are other potentially responsible parties and the Utilities are not managing the site investigation and remediation, the accrued liability represents an estimate of the amount the Utilities will need to pay to investigate and, where determinable, discharge their related obligations. For Superfund Sites (including the manufactured gas plant sites) for which one of the Utilities is managing the investigation and remediation, the accrued liability represents an estimate of the company’s share of the undiscounted cost to investigate the sites and, for sites that have been investigated in whole or in part, the cost to remediate the sites, if remediation is necessary and if a reasonable estimate of such cost can be made. Remediation costs are estimated in light of the information available, applicable remediation standards and experience with similar sites.

The accrued liabilities and regulatory assets related to Superfund Sites at September 30, 2018 and December 31, 2017 were as follows:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Accrued Liabilities:
Manufactured gas plant sites	$639	$651	$546	$551
Other Superfund Sites	81	86	80	86
Total	$720	$737	$626	$637
Regulatory assets	$754	$793	$653	$677

Most of the accrued Superfund Site liability relates to sites that have been investigated, in whole or in part. However, for some of the sites, the extent and associated cost of the required remediation has not yet been determined. As investigations progress and information pertaining to the required remediation becomes available, the Utilities expect that additional liability may be accrued, the amount of which is not presently determinable but may be material. The Utilities are permitted to recover or defer as regulatory assets (for subsequent recovery through rates) prudently incurred site investigation and remediation costs.

Environmental remediation costs incurred related to Superfund Sites for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Remediation costs incurred	$8	$4	$5	$3



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Remediation costs incurred	$17	$18	$14	$13

Insurance and other third-party recoveries received by Con Edison or CECONY were immaterial for the three and nine months ended September 30, 2018 and 2017.

In 2017, Con Edison and CECONY estimated that for their manufactured gas plant sites (including CECONY’s Astoria site), the aggregate undiscounted potential liability for the investigation and remediation of coal tar and/or other environmental contaminants could range up to $2.7 billion and $2.5 billion, respectively. These estimates were based on the assumption that there is contamination at all sites, including those that have not yet been fully investigated and additional assumptions about the extent of the contamination and the type and extent of the remediation that may be required. Actual experience may be materially different.

Asbestos Proceedings

Suits have been brought in New York State and federal courts against the Utilities and many other defendants, wherein a large number of plaintiffs sought large amounts of compensatory and punitive damages for deaths and injuries allegedly caused by exposure to asbestos at various premises of the Utilities. The suits that have been resolved, which are many, have been resolved without any payment by the Utilities, or for amounts that were not, in the aggregate, material to them. The amounts specified in all the remaining thousands of suits total billions of dollars; however, the Utilities believe that these amounts are greatly exaggerated, based on the disposition of previous claims. At September 30, 2018, Con Edison and CECONY have accrued their estimated aggregate undiscounted potential liabilities for these suits and additional suits that may be brought over the next 15 years as shown in the following table. These estimates were based upon a combination of modeling, historical data analysis and risk factor assessment. Courts have begun, and unless otherwise determined on appeal may continue, to apply different standards for determining liability in asbestos suits than the standard that applied historically. As a result, the Companies currently believe that there is a reasonable possibility of an exposure to loss in excess of the liability accrued for the suits. The Companies are unable to estimate the amount or range of such loss. In addition, certain current and former employees have claimed or are claiming workers’ compensation benefits based on alleged disability from exposure to asbestos. CECONY is permitted to defer as regulatory assets (for subsequent recovery through rates) costs incurred for its asbestos lawsuits and workers’ compensation claims.

The accrued liability for asbestos suits and workers’ compensation proceedings (including those related to asbestos exposure) and the amounts deferred as regulatory assets for the Companies at September 30, 2018 and December 31, 2017 were as follows:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Accrued liability – asbestos suits	$8	$8	$7	$7
Regulatory assets – asbestos suits	$8	$8	$7	$7
Accrued liability – workers’ compensation	$80	$84	$76	$80
Regulatory assets – workers’ compensation	$6	$10	$6	$10

Other Material Contingencies

9 Months Ended

Sep. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

Other Material Contingencies

Manhattan Explosion and Fire

On March 12, 2014, two multi-use five-story tall buildings located on Park Avenue between 116^th and 117^th Streets in Manhattan were destroyed by an explosion and fire. CECONY had delivered gas to the buildings through service lines from a distribution main located below ground on Park Avenue. Eight people died and more than 50 people were injured. Additional buildings were also damaged. The National Transportation Safety Board (NTSB) investigated. The parties to the investigation included the company, the City of New York, the Pipeline and Hazardous Materials Safety Administration and the NYSPSC. In June 2015, the NTSB issued a final report concerning the incident, its probable cause and safety recommendations. The NTSB determined that the probable cause of the incident was (1) the failure of a defective fusion joint at a service tee (which joined a plastic service line to a plastic distribution main) installed by the company that allowed gas to leak from the distribution main and migrate into a building where it ignited and (2) a breach in a City sewer line that allowed groundwater and soil to flow into the sewer, resulting in a loss of support for the distribution main, which caused it to sag and overstressed the defective fusion joint. The NTSB also made safety recommendations, including recommendations to the company that addressed its procedures for the preparation and examination of plastic fusions, training of its staff on conditions for notifications to the City’s Fire Department and extension of its gas main isolation valve installation program. In February 2017, the NYSPSC approved a settlement agreement with the company related to the NYSPSC's investigations of the incident and the practices of qualifying persons to perform plastic fusions. Pursuant to the agreement, the company is providing $27 million of future benefits to customers (for which it has accrued a regulatory liability) and will not recover from customers $126 million of costs for gas emergency response activities that it had previously incurred and expensed. Approximately eighty suits are pending against the company seeking generally unspecified damages and, in some cases, punitive damages, for wrongful death, personal injury, property damage and business interruption. The company has notified its insurers of the incident and believes that the policies in force at the time of the incident will cover the company’s costs, in excess of a required retention (the amount of which is not material), to satisfy any liability it may have for damages in connection with the incident. The company is unable to estimate the amount or range of its possible loss for damages related to the incident. At September 30, 2018, the company had not accrued a liability for damages related to the incident.

Manhattan Steam Main Rupture

In July 2018, a CECONY steam main located on Fifth Avenue and 21^st street in Manhattan ruptured. Debris from the incident included dirt and mud containing asbestos. The response to the incident required the closing of buildings and streets for various periods. The NYSPSC has commenced an investigation. As of September 30, 2018, with respect to the incident, the company incurred estimated operating costs of $10 million for property damage, clean- up and other response costs and invested $7 million in capital and retirement costs. The company has notified its insurers of the incident and believes that the policies currently in force will cover the company’s costs, in excess of a required retention (the amount of which is not material), to satisfy any liability it may have for damages to others in connection with the incident. The company is unable to estimate the amount or range of its possible loss related to the incident. At September 30, 2018, the company had not accrued a liability related to the incident.

Other Contingencies

See "Other Regulatory Matters" in Note B and “Uncertain Tax Positions” in Note I.

Guarantees

Con Edison has guaranteed the obligations of a Con Edison Development subsidiary under the purchase and sale agreement for its acquisition of Sempra Solar Holdings, LLC, including the payment of the purchase price for the acquisition ($1,540 million, subject to closing adjustments, including working capital). See Note O.

Con Edison and its subsidiaries have entered into various other agreements providing financial or performance assurance primarily to third parties on behalf of their subsidiaries. Maximum amounts guaranteed by Con Edison under these other agreements totaled $1,991 million and $2,073 million at September 30, 2018 and December 31, 2017, respectively.

A summary, by type and term, of Con Edison’s total guarantees under these other agreements at September 30, 2018 is as follows:



Guarantee Type	0 – 3 years	4 – 10 years	> 10 years		Total
	(Millions of Dollars)
Con Edison Transmission	$744	$404		$—	$1,148
Energy transactions	434	24	201		659
Renewable electric production projects	93	—	21		114
Other	70	—	—		70
Total	$1,341	$428	$222		$1,991

Con Edison Transmission — Con Edison has guaranteed payment by CET Electric of the contributions CET Electric agreed to make to New York Transco LLC (NY Transco). CET Electric acquired a 45.7 percent interest in NY Transco when it was formed in 2014. In May 2016, the transmission owners transferred certain projects to NY Transco, for which CET Electric made its required contributions. NY Transco has proposed other transmission projects in the New York Independent System Operator's competitive bidding process. These other projects are subject to certain authorizations from the NYSPSC, the FERC and, as applicable, other federal, state and local agencies. Guarantee amount shown is for the maximum possible required amount of CET Electric’s contributions for these other projects as calculated based on the assumptions that the projects are completed at 175 percent of their estimated costs and NY Transco does not use any debt financing for the projects. Guarantee term shown is assumed as the selection of the projects and resulting timing of the contributions is not certain. Also included within the table above are guarantees for $125 million from Con Edison on behalf of CET Gas in relation to a proposed gas transmission project in West Virginia and Virginia.

Energy Transactions — Con Edison guarantees payments on behalf of the Clean Energy Businesses in order to facilitate physical and financial transactions in electricity, gas, pipeline capacity, transportation, oil, renewable energy credits and energy services. To the extent that liabilities exist under the contracts subject to these guarantees, such liabilities are included in Con Edison’s consolidated balance sheet.

Renewable Electric Production Projects — Con Edison, Con Edison Development, and Con Edison Solutions guarantee payments on behalf of their wholly-owned subsidiaries associated with their investment in, or development for others of, solar and wind energy facilities.

Other — Other guarantees include $70 million in guarantees provided by Con Edison to Travelers Insurance Company for indemnity agreements for surety bonds in connection with operation of solar energy facilities and energy service projects of Con Edison Development and Con Edison Solutions, respectively.

Income Tax

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Income Tax

Con Edison’s income tax expense decreased to $175 million for the three months ended September 30, 2018 from $270 million for the three months ended September 30, 2017. CECONY’s income tax expense decreased to $125 million for the three months ended September 30, 2018 from $242 million for the three months ended September 30, 2017. The decrease in income tax expense for both Companies is due primarily to lower income before income tax expense, the lower corporate federal income tax rate of 21 percent in 2018 resulting from the enactment of the TCJA and an increase in the amortization of excess deferred federal income taxes due to the TCJA. Con Edison’s decrease in income tax expense was offset in part by $42 million of income tax expense which, as discussed below, resulted from newly issued guidance on the TCJA and the subsequent re-measurement of deferred tax assets associated with Con Edison’s 2017 federal net operating loss (NOL) carryover into 2018.

Reconciliation of the difference between income tax expense and the amount computed by applying the prevailing statutory income tax rate to income before income taxes for the three months ended September 30, is as follows:



	Con Edison				CECONY
(% of Pre-tax income)	2018		2017		2018		2017
STATUTORY TAX RATE
Federal	21	%	35	%	21	%	35	%
Changes in computed taxes resulting from:
State income tax	5		5		5		4
Other plant-related items	(1	)	(1	)	(1	)	(1	)
Renewable energy credits	(1	)	(1	)	—		—
TCJA deferred tax re-measurement	7		—		—		—
Amortization of excess deferred federal income taxes	(2	)	—		(2	)	—
Other	(1	)	(1	)	(1	)	—
Effective tax rate	28	%	37	%	22	%	38	%

Con Edison’s income tax expense decreased to $330 million for the nine months ended September 30, 2018 from $599 million for the nine months ended September 30, 2017. CECONY’s income tax expense decreased to $274 million for the nine months ended September 30, 2018 from $551 million for the nine months ended September 30, 2017. The decrease in income tax expense for both Companies is due primarily to lower income before income tax expense, the lower corporate federal income tax rate of 21 percent in 2018 resulting from the enactment of the TCJA and an increase in the amortization of excess deferred federal income taxes due to the TCJA. Con Edison’s decrease in income tax expense was offset in part by $42 million of income tax expense which, as discussed below, resulted from newly issued guidance on the TCJA and the subsequent re-measurement of deferred tax assets associated with Con Edison’s 2017 federal NOL carryover into 2018.

Reconciliation of the difference between income tax expense and the amount computed by applying the prevailing statutory income tax rate to income before income taxes for the nine months ended September 30, is as follows:



	Con Edison				CECONY
(% of Pre-tax income)	2018		2017		2018		2017
STATUTORY TAX RATE
Federal	21	%	35	%	21	%	35	%
Changes in computed taxes resulting from:
State income tax	5		4		5		4
Cost of removal	1		1		1		1
Other plant-related items	(1	)	(1	)	(1	)	(1	)
Renewable energy credits	(1	)	(1	)	—		—
TCJA deferred tax re-measurement	3		—		—		—
Amortization of excess deferred federal income taxes	(3	)	—		(3	)	—
Other	(1	)	(1	)	(1	)	(1	)
Effective tax rate	24	%	37	%	22	%	38	%

CECONY and O&R deferred as regulatory liabilities their estimated net benefits under the TCJA for the nine months ended September 30, 2018. RECO deferred as a regulatory liability its estimated net benefits under the TCJA for the three months ended March 31, 2018. The net benefits include the revenue requirement impact of the reduction in the corporate federal income tax rate to 21 percent, the elimination for utilities of bonus depreciation and the amortization of excess deferred federal income taxes the utilities collected from customers that will not need to be paid to the Internal Revenue Service under the TCJA. See “Other Regulatory Matters” in Note B.

At December 31, 2017, the Companies recorded provisional income tax amounts in its accounting for certain effects of the provisions of the TCJA as allowed under SEC Staff Accounting Bulletin 118 (SAB 118). SAB 118 allowed a one year period for companies to finalize the provisional amounts recorded as of December 31, 2017. In August 2018, the Internal Revenue Service and U.S. Department of Treasury issued proposed regulations that clarified provisions in TCJA on the allowance for additional first-year depreciation for qualified property of regulated public utilities placed in service in the fourth quarter of 2017. Under this guidance, the Utilities deducted $477 million in additional depreciation in Con Edison’s 2017 federal income tax return. The additional depreciation increased Con Edison’s 2017 federal NOL carryover to $563 million (CECONY’s 2017 federal NOL carryover is $153 million), which required a re-measurement of deferred tax assets and liabilities associated with the filing of its 2017 federal income tax return. As a result, Con Edison decreased its net deferred tax liabilities by $16 million (including $51 million for CECONY), recognized $42 million in income tax expense at the parent company related to re-measuring the 2017 federal NOL carryover to 2018 and accrued a regulatory liability for future income tax of $58 million (including $51 million for CECONY). The Companies expect to complete their assessment and record any final adjustments to the provisional amounts by the fourth quarter of 2018.

Uncertain Tax Positions

In March 2018, Con Edison received approval of its tax refunds by the Joint Committee on Taxation for tax years 2012 through 2015. The approval effectively settled approximately $3 million in uncertain federal tax positions. Federal income tax returns for 2016 and 2017 remain under examination.

At September 30, 2018, the estimated liability for uncertain tax positions for Con Edison was $11 million ($5 million for CECONY). Con Edison reasonably expects to resolve within the next twelve months approximately $10 million ($9 million, net of federal taxes) of various federal and state uncertainties due to the expected completion of ongoing tax examinations, resolution of state refund claims and expiration of statute of limitations, of which the entire amount, if recognized, would reduce Con Edison's effective tax rate. The amount related to CECONY is approximately $3 million, which, if recognized, would reduce CECONY’s effective tax rate. The total amount of unrecognized tax benefits, if recognized, that would reduce Con Edison’s effective tax rate is $11 million ($10 million, net of federal taxes).

The Companies recognize interest on liabilities for uncertain tax positions in interest expense and would recognize penalties, if any, in operating expenses in the Companies’ consolidated income statements. In the three and nine months ended September 30, 2018, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At September 30, 2018 and December 31, 2017, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.

Financial Information by Business Segment

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Financial Information by Business Segment

Con Edison’s principal business segments are CECONY’s regulated utility activities, O&R’s regulated utility activities, the Clean Energy Businesses and Con Edison Transmission. CECONY’s principal business segments are its regulated electric, gas and steam utility activities. The financial data for the business segments for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Operating revenues		Inter-segment revenues				Depreciation and amortization		Operating income/(loss)
(Millions of Dollars)	2018	2017	2018		2017		2018	2017	2018	2017
CECONY
Electric	$2,571	$2,469	$4		$4		$248	$232	$850	$883
Gas	264	268	2		2		52	47	(34)	(6)
Steam	64	62	19		19		22	21	(52)	(41)
Consolidation adjustments	—	—	(25)		(25)		—	—	—	—
Total CECONY	$2,899	$2,799		$—		$—	$322	$300	$764	$836
O&R
Electric	$212	$206		$—		$—	$14	$13	$52	$60
Gas	34	28	—		—		5	5	(10)	(10)
Total O&R	$246	$234		$—		$—	$19	$18	$42	$50
Clean Energy Businesses	$181	$177		$—		$—	$18	$19	$25	$29
Con Edison Transmission	1	1	—		—		—	—	(2)	(2)
Other (a)	1	—	—		—		1	—	(3)	1
Total Con Edison	$3,328	$3,211		$—		$—	$360	$337	$826	$914



	For the Nine Months Ended September 30,
	Operating revenues		Inter-segment revenues				Depreciation and amortization		Operating income/(loss)
(Millions of Dollars)	2018	2017	2018		2017		2018	2017	2018	2017
CECONY
Electric	$6,107	$6,079	$12		$12		$732	$690	$1,421	$1,561
Gas	1,540	1,421	6		5		152	137	369	379
Steam	474	448	56		55		65	64	60	59
Consolidation adjustments	—	—	(74)		(72)		—	—	—	—
Total CECONY	$8,121	$7,948		$—		$—	$949	$891	$1,850	$1,999
O&R
Electric	$505	$495		$—		$—	$41	$38	$79	$94
Gas	186	172	—		—		16	15	31	37
Total O&R	$691	$667		$—		$—	$57	$53	$110	$131
Clean Energy Businesses	573	460	—		—		55	54	59	63
Con Edison Transmission	3	1	—		—		1	—	(5)	(6)
Other (a)	—	(4)	—		—		(1)	—	(7)	2
Total Con Edison	$9,388	$9,072		$—		$—	$1,061	$998	$2,007	$2,189

(a) Parent company and consolidation adjustments. Other does not represent a business segment.

Derivative Instruments and Hedging Activities

9 Months Ended

Sep. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities

Con Edison’s subsidiaries hedge market price fluctuations associated with physical purchases and sales of electricity, natural gas, steam and, to a lesser extent, refined fuels by using derivative instruments including futures, forwards, basis swaps, options, transmission congestion contracts and financial transmission rights contracts. Derivatives are recognized on the consolidated balance sheet at fair value (see Note L), unless an exception is available under the accounting rules for derivatives and hedging. Qualifying derivative contracts that have been designated as normal purchases or normal sales contracts are not reported at fair value under the accounting rules.

The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2018 and December 31, 2017 were:



(Millions of Dollars)	2018					2017
Balance Sheet Location	Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)		Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)
Con Edison
Fair value of derivative assets
Current	$45	$(23)		$22	(b)	$83	$(51)		$32	(b)
Noncurrent	21	(13)		8		10	(4)		6
Total fair value of derivative assets	$66	$(36)		$30		$93	$(55)		$38
Fair value of derivative liabilities
Current	$(41)	$23		$(18)		$(67)	$50		$(17)
Noncurrent	(26)	13		(13)		(43)	5		(38)
Total fair value of derivative liabilities	$(67)	$36		$(31)		$(110)	$55		$(55)
Net fair value derivative assets/(liabilities)	$(1)		$—	$(1)	(b)	$(17)		$—	$(17)	(b)
CECONY
Fair value of derivative assets
Current	$32	$(16)		$16	(b)	$39	$(15)		$24	(b)
Noncurrent	16	(11)		5		9	(4)		5
Total fair value of derivative assets	$48	$(27)		$21		$48	$(19)		$29
Fair value of derivative liabilities
Current	$(19)	$15		$(4)		$(26)	$14		$(12)
Noncurrent	(20)	11		(9)		(36)	4		(32)
Total fair value of derivative liabilities	$(39)	$26		$(13)		$(62)	$18		$(44)
Net fair value derivative assets/(liabilities)	$9	$(1)		$8	(b)	$(14)	$(1)		$(15)	(b)

(a)

Derivative instruments and collateral were offset on the consolidated balance sheet as applicable under the accounting rules. The Companies enter into master agreements for their commodity derivatives. These agreements typically provide offset in the event of contract termination. In such case, generally the non-defaulting party’s payable will be offset by the defaulting party’s payable. The non-defaulting party will customarily notify the defaulting party within a specific time period and come to an agreement on the early termination amount.

(b)

At September 30, 2018 and December 31, 2017, margin deposits for Con Edison ($7 million and $12 million, respectively) and CECONY ($6 million and $11 million, respectively) were classified as derivative assets on the consolidated balance sheet, but not included in the table. Margin is collateral, typically cash, that the holder of a derivative instrument is required to deposit in order to transact on an exchange and to cover its potential losses with its broker or the exchange.

The Utilities generally recover their prudently incurred fuel, purchased power and gas costs, including hedging gains and losses, in accordance with rate provisions approved by the applicable state utility regulators. In accordance with the accounting rules for regulated operations, the Utilities record a regulatory asset or liability to defer recognition of unrealized gains and losses on their electric and gas derivatives. As gains and losses are realized in future periods, they will be recognized as purchased power, gas and fuel costs in the Companies’ consolidated income statements. The Clean Energy Businesses record realized and unrealized gains and losses on their derivative contracts in purchased power, gas purchased for resale and non-utility revenue in the reporting period in which they occur. Management believes that these derivative instruments represent economic hedges that mitigate exposure to fluctuations in commodity prices.

The following table presents the realized and unrealized gains or losses on commodity derivatives that have been deferred or recognized in earnings for the three and nine months ended September 30, 2018 and 2017:



		For the Three Months Ended September 30,
		Con Edison						CECONY
(Millions of Dollars)	Balance Sheet Location	2018			2017			2018		2017
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Current	Deferred derivative gains	$6			$(4)			$6		$(3)
Noncurrent	Deferred derivative gains	—			1			2		1
Total deferred gains/(losses)		$6			$(3)			$8		$(2)
Current	Deferred derivative losses	$25			$(11)			$25		$(9)
Current	Recoverable energy costs	(4)			(40)			(6)		(38)
Noncurrent	Deferred derivative losses	15			(12)			14		(8)
Total deferred gains/(losses)		$36			$(63)			$33		$(55)
Net deferred gains/(losses)		$42			$(66)			$41		$(57)
	Income Statement Location
Pre-tax gains/(losses) recognized in income
	Purchased power expense		$—			$—			$—		$—
	Gas purchased for resale	—			(47)			—		—
	Non-utility revenue	(7)		(a)	5		(b)	—		—
Total pre-tax gains/(losses) recognized in income		$(7)			$(42)				$—		$—


(a)	For the three months ended September 30, 2018, Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ($4 million).


(b)	For the three months ended September 30, 2017, Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ($6 million).



		For the Nine Months Ended September 30,
		Con Edison						CECONY
(Millions of Dollars)	Balance Sheet Location	2018			2017			2018		2017
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Current	Deferred derivative gains	$(11)			$(26)			$(10)		$(22)
Noncurrent	Deferred derivative gains	5			(2)			4		(2)
Total deferred gains/(losses)		$(6)			$(28)			$(6)		$(24)
Current	Deferred derivative losses	$21			$10			$23		$11
Current	Recoverable energy costs	(13)			(125)			(14)		(116)
Noncurrent	Deferred derivative losses	23			(40)			21		(36)
Total deferred gains/(losses)		$31			$(155)			$30		$(141)
Net deferred gains/(losses)		$25			$(183)			$24		$(165)
	Income Statement Location
Pre-tax gains/(losses) recognized in income
	Purchased power expense		$—			$—			$—		$—
	Gas purchased for resale	(1)			(161)			—		—
	Non-utility revenue	(7)		(a)	11		(b)	—		—
Total pre-tax gains/(losses) recognized in income		$(8)			$(150)				$—		$—


(a)	For the nine months ended September 30, 2018, Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ($6 million).


(b)	For the nine months ended September 30, 2017, Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ($2 million).

The following table presents the hedged volume of Con Edison’s and CECONY’s derivative transactions at September 30, 2018:



	Electric Energy (MWh) (a)(b)	Capacity (MW) (a)	Natural Gas (Dt) (a)(b)	Refined Fuels (gallons)
Con Edison	30,590,984	8,134	195,821,882	2,688,000
CECONY	27,983,800	3,300	182,820,000	2,688,000


(a)	Volumes are reported net of long and short positions, except natural gas collars where the volumes of long positions are reported.


(b)	Excludes electric congestion and gas basis swap contracts, which are associated with electric and gas contracts and hedged volumes.

The Companies are exposed to credit risk related to transactions entered into primarily for the various energy supply and hedging activities by the Utilities and the Clean Energy Businesses. Credit risk relates to the loss that may result from a counterparty’s nonperformance. The Companies use credit policies to manage this risk, including an established credit approval process, monitoring of counterparty limits, netting provisions within agreements, collateral or prepayment arrangements, credit insurance and credit default swaps. The Companies measure credit risk exposure as the replacement cost for open energy commodity and derivative positions plus amounts owed from counterparties for settled transactions. The replacement cost of open positions represents unrealized gains, net of any unrealized losses where the Companies have a legally enforceable right to offset.

At September 30, 2018, Con Edison and CECONY had $107 million and $17 million of credit exposure in connection with energy supply and hedging activities, net of collateral, respectively. Con Edison’s net credit exposure consisted of $44 million with independent system operators, $25 million with investment-grade counterparties, $22 million with non-investment grade/non-rated counterparties and $16 million with commodity exchange brokers. CECONY’s net credit exposure consisted of $10 million with investment-grade counterparties and $7 million with commodity exchange brokers.

The collateral requirements associated with, and settlement of, derivative transactions are included in net cash flows from operating activities in the Companies’ consolidated statement of cash flows. Most derivative instrument contracts contain provisions that may require a party to provide collateral on its derivative instruments that are in a net liability position. The amount of collateral to be provided will depend on the fair value of the derivative instruments and the party’s credit ratings.

The following table presents the aggregate fair value of the Companies’ derivative instruments with credit-risk-related contingent features that are in a net liability position, the collateral posted for such positions and the additional collateral that would have been required to be posted had the lowest applicable credit rating been reduced one level and to below investment grade at September 30, 2018:



(Millions of Dollars)	Con Edison (a)		CECONY (a)
Aggregate fair value – net liabilities	$19		$9
Collateral posted	13		10
Additional collateral (b) (downgrade one level from current ratings)	—		—
Additional collateral (b) (downgrade to below investment grade from current ratings)	17	(c)	7	(c)

(a)

Non-derivative transactions for the purchase and sale of electricity and gas and qualifying derivative instruments, which have been designated as normal purchases or normal sales, are excluded from the table. These transactions primarily include purchases of electricity from independent system operators. In the event the Utilities and the Clean Energy Businesses were no longer extended unsecured credit for such purchases, the Companies would be required to post additional collateral of $1 million at September 30, 2018. For certain other such non-derivative transactions, the Companies could be required to post collateral under certain circumstances, including in the event counterparties had reasonable grounds for insecurity.

(b)

The Companies measure the collateral requirements by taking into consideration the fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position plus amounts owed to counterparties for settled transactions and amounts required by counterparties for minimum financial security. The fair value amounts represent unrealized losses, net of any unrealized gains where the Companies have a legally enforceable right to offset.


(c)	Derivative instruments that are net assets have been excluded from the table. At September 30, 2018, if Con Edison had been downgraded to below investment grade, it would have been required to post additional collateral for such derivative instruments of $22 million.

Interest Rate Swap

In December 2016, the Clean Energy Businesses acquired Coram Wind which holds an interest rate swap that terminates in June 2024, pursuant to which it pays a fixed-rate of 2.0855 percent and receives a LIBOR-based variable rate. The fair value of this interest rate swap was an asset of $1 million as of September 30, 2018 and an immaterial amount as of December 31, 2017 on Con Edison’s consolidated balance sheet.

Fair Value Measurements

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

The accounting rules for fair value measurements and disclosures define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable firm inputs. The Companies often make certain assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. The Companies use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs.

The accounting rules for fair value measurements and disclosures established a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The rules require that assets and liabilities be classified in their entirety based on the level of input that is significant to the fair value measurement. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and their placement within the fair value hierarchy. The Companies classify fair value balances based on the fair value hierarchy defined by the accounting rules for fair value measurements and disclosures as follows:

•

Level 1 – Consists of assets or liabilities whose value is based on unadjusted quoted prices in active markets at the measurement date. An active market is one in which transactions for assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes contracts traded on active exchange markets valued using unadjusted prices quoted directly from the exchange.

•

Level 2 – Consists of assets or liabilities valued using industry standard models and based on prices, other than quoted prices within Level 1, that are either directly or indirectly observable as of the measurement date. The industry standard models consider observable assumptions including time value, volatility factors and current market and contractual prices for the underlying commodities, in addition to other economic measures. This category includes contracts traded on active exchanges or in over-the-counter markets priced with industry standard models.

•

Level 3 – Consists of assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost benefit constraints. This category includes contracts priced using models that are internally developed and contracts placed in illiquid markets. It also includes contracts that expire after the period of time for which quoted prices are available and internal models are used to determine a significant portion of the value.

Assets and liabilities measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 are summarized below.



	2018					2017
(Millions of Dollars)	Level 1	Level 2	Level 3	Netting Adjustment (e)	Total	Level 1	Level 2	Level 3		Netting Adjustment (e)	Total
Con Edison
Derivative assets:
Commodity (a)(b)(c)	$3	$40	$8	$(14)	$37	$5	$77	$7		$(39)	$50
Interest rate swap (a)(b)(c)	—	1	—	—	1	—	—	—		—	—
Other (a)(b)(d)	314	119	—	—	433	283	120	—		—	403
Total assets	$317	$160	$8	$(14)	$471	$288	$197	$7		$(39)	$453
Derivative liabilities:
Commodity (a)(b)(c)	$5	$30	$18	$(22)	$31	$8	$93	$6		$(52)	$55
CECONY
Derivative assets:
Commodity (a)(b)(c)	$3	$33	$1	$(10)	$27	$3	$40	$4		$(7)	$40
Other (a)(b)(d)	293	113	—	—	406	260	114	—		—	374
Total assets	$296	$146	$1	$(10)	$433	$263	$154	$4		$(7)	$414
Derivative liabilities:
Commodity (a)(b)(c)	$4	$22	$1	$(14)	$13	$5	$57		$—	$(18)	$44

(a)

The Companies’ policy is to review the fair value hierarchy and recognize transfers into and transfers out of the levels at the end of each reporting period. Con Edison and CECONY had $1 million of net commodity derivative liabilities transferred from level 3 to level 2 during the nine months ended September 30, 2018 because of availability of observable market data due to the decrease in the terms of certain contracts from beyond three years as of December 31, 2017 to less than three years as of September 30, 2018. Con Edison and CECONY had $11 million and $10 million, respectively, of commodity derivative liabilities transferred from level 3 to level 2 during the year ended December 31, 2017 because of availability of observable market data due to the decrease in the terms of certain contracts from beyond three years as of September 30, 2017 to less than three years as of December 31, 2017.

(b)

Level 2 assets and liabilities include investments held in the deferred compensation plan and/or non-qualified retirement plans, exchange-traded contracts where there is insufficient market liquidity to warrant inclusion in Level 1, certain over-the-counter derivative instruments for electricity, refined products and natural gas. Derivative instruments classified as Level 2 are valued using industry standard models that incorporate corroborated observable inputs; such as pricing services or prices from similar instruments that trade in liquid markets, time value and volatility factors.

(c)

The accounting rules for fair value measurements and disclosures require consideration of the impact of nonperformance risk (including credit risk) from a market participant perspective in the measurement of the fair value of assets and liabilities. At September 30, 2018 and December 31, 2017, the Companies determined that nonperformance risk would have no material impact on their financial position or results of operations.


(d)	Other assets are comprised of assets such as life insurance contracts within the deferred compensation plan and non-qualified retirement plans.


(e)	Amounts represent the impact of legally-enforceable master netting agreements that allow the Companies to net gain and loss positions and cash collateral held or placed with the same counterparties.

The employees in the Companies’ risk management group develop and maintain the Companies’ valuation policies and procedures for, and verify pricing and fair value valuation of, commodity derivatives. Under the Companies’ policies and procedures, multiple independent sources of information are obtained for forward price curves used to value commodity derivatives. Fair value and changes in fair value of commodity derivatives are reported on a monthly basis to the Companies’ risk committees, comprised of officers and employees of the Companies that oversee energy hedging at the Utilities and the Clean Energy Businesses. The risk management group reports to the Companies’ Vice President and Treasurer.



	Fair Value of Level 3 at September 30, 2018		Valuation Techniques	Unobservable Inputs	Range
	(Millions of Dollars)		Valuation Techniques	Unobservable Inputs	Range
Con Edison – Commodity
Electricity	$(7)		Discounted Cash Flow	Forward energy prices (a)	$18.33-$79.20 per MWh
			Discounted Cash Flow	Forward capacity prices (a)	$1.70-$8.84 per kW-month
Natural Gas	(4)		Discounted Cash Flow	Forward natural gas prices (a)	$0.96-$10.51 per Dt
Transmission Congestion Contracts/Financial Transmission Rights	1		Discounted Cash Flow	Inter-zonal forward price curves adjusted for historical zonal losses (b)	$0.37-$5.45 per MWh
Total Con Edison—Commodity	$(10)
CECONY – Commodity
Electricity	$(1)		Discounted Cash Flow	Forward capacity prices (a)	$1.70-$7.20 per kW-month
Transmission Congestion Contracts	1		Discounted Cash Flow	Inter-zonal forward price curves adjusted for historical zonal losses (b)	$0.45-$4.18 per MWh
Total CECONY—Commodity		$—


(a)	Generally, increases/(decreases) in this input in isolation would result in a higher/(lower) fair value measurement.


(b)	Generally, increases/(decreases) in this input in isolation would result in a lower/(higher) fair value measurement.

The table listed below provides a reconciliation of the beginning and ending net balances for assets and liabilities measured at fair value as of September 30, 2018 and 2017 and classified as Level 3 in the fair value hierarchy:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018		2017
Beginning balance as of July 1,	$(4)	$(10)		$—	$(6)
Included in earnings	4	7	2		1
Included in regulatory assets and liabilities	(4)	(13)	—		(8)
Settlements	(6)	(4)	(2)		(1)
Ending balance as of September 30,	$(10)	$(20)		$—	$(14)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018		2017
Beginning balance as of January 1,	$1	$1	$4		$1
Included in earnings	4	8	4		1
Included in regulatory assets and liabilities	(7)	(21)	(5)		(14)
Purchases	—	1	—		1
Settlements	(9)	(9)	(4)		(3)
Transfer out of level 3	1	—	1		—
Ending balance as of September 30,	$(10)	$(20)		$—	$(14)

For the Utilities, realized gains and losses on Level 3 commodity derivative assets and liabilities are reported as part of purchased power, gas and fuel costs. The Utilities generally recover these costs in accordance with rate provisions approved by the applicable state public utilities regulators. Unrealized gains and losses for commodity derivatives are generally deferred on the consolidated balance sheet in accordance with the accounting rules for regulated operations.

For the Clean Energy Businesses, realized and unrealized gains and losses on Level 3 commodity derivative assets and liabilities are reported in non-utility revenues ($1 million loss and immaterial) and purchased power costs (immaterial and $4 million gain) on the consolidated income statement for the three months ended September 30, 2018 and 2017, respectively. Realized and unrealized gains and losses on Level 3 commodity derivative assets and liabilities are reported in non-utility revenues ($4 million loss and immaterial) and purchased power costs (immaterial and $3 million gain) on the consolidated income statement for the nine months ended September 30, 2018 and 2017, respectively. The change in fair value relating to Level 3 commodity derivative assets and liabilities held at September 30, 2018 and 2017 is included in non-utility revenues ($1 million loss and immaterial) and purchased power costs (immaterial and $4 million gain) on the consolidated income statement for the three months ended September 30, 2018 and 2017, respectively. For the nine months ended September 30, 2018 and 2017, the change in fair value relating to Level 3 commodity derivative assets and liabilities is included in non-utility revenues ($5 million loss and immaterial) and purchased power costs (immaterial and $2 million gain), respectively, on the consolidated income statement.

Variable Interest Entities

9 Months Ended

Sep. 30, 2018

Equity Method Investments and Joint Ventures [Abstract]

Variable Interest Entities

Con Edison enters into arrangements including leases, partnerships and electricity purchase agreements, with various entities. As a result of these arrangements, Con Edison retains or may retain a variable interest in these entities.

CECONY has an ongoing long-term electricity purchase agreement with Brooklyn Navy Yard Cogeneration Partners, LP, a potential variable interest entity (VIE). In 2017, a request was made of this counterparty for information necessary to determine whether the entity was a VIE and whether CECONY is the primary beneficiary; however, the information was not made available. The payments for this contract constitute CECONY’s maximum exposure to loss with respect to the potential VIE.

The following table summarizes the VIEs in which Con Edison Development has entered into as of September 30, 2018:



Project Name (a)	Generating Capacity (b) (MW AC)	Power Purchase Agreement Term (in Years)	Year of Initial Investment	Location	Maximum Exposure to Loss (Millions of Dollars) (c)
Copper Mountain Solar 3 (d)	128	20	2014	Nevada	$169
Mesquite Solar 1 (d)	83	20	2013	Arizona	101
Copper Mountain Solar 2 (d)	75	25	2013	Nevada	80
California Solar (d)	55	25	2012	California	59
Broken Bow II (d)	38	25	2014	Nebraska	42
Texas Solar 4	32	25	2014	Texas	19

(a) With the exception of Texas Solar 4, Con Edison’s ownership interest is 50 percent and these projects are accounted for using the equity method of accounting. With the exception of Texas Solar 4, Con Edison is not the primary beneficiary since the power to direct the activities that most significantly impact the economics of the entities are shared equally between Con Edison Development and third parties. Con Edison’s ownership interest in Texas Solar 4 is 80 percent and is consolidated in the financial statements. Con Edison is the primary beneficiary since the power to direct the activities that most significantly impact the economics of Texas Solar 4 is held by Con Edison Development.

(b) Represents Con Edison Development’s ownership interest in the project.

(c) For investments accounted for under the equity method, maximum exposure is equal to the carrying value of the investment on the consolidated balance sheet. For consolidated investments, such as Texas Solar 4, maximum exposure is equal to the net assets of the project on the consolidated balance sheet less any applicable noncontrolling interest ($7 million for Texas Solar 4). Con Edison did not provide any financial or other support during the three and nine months ended September 30, 2018 that was not previously contractually required.


(d)	In September 2018, a Con Edison Development subsidiary agreed to purchase Sempra Solar Holdings, LLC, subsidiaries of which have a 50 percent ownership interest in these projects. Upon the closing of the acquisition, Con Edison expects to account for these projects on a consolidated basis. See Note O.

New Financial Accounting Standards	9 Months Ended
New Financial Accounting Standards	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
New Financial Accounting Standards	New Financial Accounting Standards In February 2016, the FASB issued amendments on financial reporting of leasing transactions through Accounting Standards Update (ASU) No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). The Utilities, as regulated entities, are permitted to continue to recognize expense using the timing that conforms to the regulatory rate treatment. Lessor accounting is similar to the current model, but updated to align with “Revenue from Contracts with Customers (Topic 606)." The amendments are effective, and the Companies plan to adopt the amendments, for reporting periods beginning after December 15, 2018. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Upon adoption of the amendments, the Companies expect to elect the following practical expedients: (1) for leases commenced prior to adoption date, the following three transition expedients that will allow the Companies to not reassess: (a) whether expired contracts contain leases; (b) the lease classification for expired leases and (c) the initial direct costs for existing leases; (2) if elected for an underlying asset class, an expedient that will allow the Companies to not apply the recognition requirements to short-term leases and an expedient that will allow the Companies to account for lease and associated non-lease components as a single lease component; (3) an expedient that allows the use of hindsight to determine lease term; and (4) an expedient that will allow the Companies to not evaluate under Topic 842 land easements that exist or expired before the entity’s adoption of Topic 842 and that were not previously accounted for as leases under the current lease standard. For leases currently classified as operating leases, upon adoption of the amendments, the Companies expect to recognize on their balance sheets right-of-use assets and lease liabilities. The adoption of the amendments is not expected to have a material effect on the Companies’ liquidity. The Companies are continuing to evaluate the potential impact of the amendments on the Companies’ results of operations and the additional disclosures required. The Companies will implement additional internal controls related to the amendments, however the adoption of the amendments is not expected to require a change that will materially affect the Companies’ internal control over financial reporting. In August 2017, the FASB issued amendments to the guidance for derivatives and hedging through ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” The amendments in this update provide greater clarification on hedge accounting for risk components, presentation and disclosure of hedging instruments, and overall targeted improvements to simplify hedge accounting. For public entities, the amendments are effective, and the Companies plan to adopt the amendments, for reporting periods beginning after December 15, 2018. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity. In February 2018, the FASB issued amendments to the guidance for reporting comprehensive income through ASU 2018-02, “Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” The amendments allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018, with early adoption permitted. The Companies are electing to adopt the amendments in the fourth quarter of 2018. The impact of adoption on the Companies’ financial position, results of operations and liquidity is expected to be immaterial. In August 2018, the FASB issued amendments to the guidance for internal use software through ASU 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract.” The amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019, with early adoption permitted. The Companies elected to adopt the amendments in the third quarter of 2018, prospectively for all in-scope implementation costs incurred after the date of adoption. The impact of adoption on the Companies’ financial position, results of operations and liquidity was immaterial.

Acquisitions	9 Months Ended
Acquisitions	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions In September 2018, a Con Edison Development subsidiary agreed to purchase Sempra Solar Holdings, LLC, a Sempra Energy subsidiary, for $1,540 million, subject to closing adjustments, including working capital. Sempra Solar Holdings, LLC has ownership interests in 981 megawatts (AC) of operating renewable electric production projects, including its 379 megawatts (AC) share of projects in which its subsidiaries have a 50 percent ownership interest and Con Edison Development subsidiaries have the remaining ownership interests (see Note M), and certain development rights with respect to solar electric production and energy storage projects. Most of the operating projects that are not jointly-owned have tax equity investors to which a percentage of earnings, tax attributes and cash flows are allocated. Sempra Solar Holdings, LLC subsidiaries have $576 million of existing project debt, including project debt associated with their share of the jointly-owned projects. Con Edison Development subsidiaries have $506 million of existing project debt associated with their share of the jointly-owned projects. Con Edison has been accounting for the interests of Con Edison Development subsidiaries in the jointly-owned projects under the equity method. Upon the closing of the acquisition, Con Edison expects to account for these projects and the other projects acquired on a consolidated basis. The acquisition is subject to customary closing conditions, including, among other things, expiration or early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the approvals of the FERC and the U.S. Department of Energy. Several banks have committed to provide bridge financing for the acquisition, subject to certain customary conditions. Con Edison has guaranteed the obligations of the Con Edison Development subsidiary under the purchase and sale agreement for the acquisition, including the payment of the purchase price for the acquisition. See Note H.

New Financial Accounting Standards (Policies)	9 Months Ended
New Financial Accounting Standards (Policies)	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
New Financial Accounting Standards	New Financial Accounting Standards In February 2016, the FASB issued amendments on financial reporting of leasing transactions through Accounting Standards Update (ASU) No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). The Utilities, as regulated entities, are permitted to continue to recognize expense using the timing that conforms to the regulatory rate treatment. Lessor accounting is similar to the current model, but updated to align with “Revenue from Contracts with Customers (Topic 606)." The amendments are effective, and the Companies plan to adopt the amendments, for reporting periods beginning after December 15, 2018. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Upon adoption of the amendments, the Companies expect to elect the following practical expedients: (1) for leases commenced prior to adoption date, the following three transition expedients that will allow the Companies to not reassess: (a) whether expired contracts contain leases; (b) the lease classification for expired leases and (c) the initial direct costs for existing leases; (2) if elected for an underlying asset class, an expedient that will allow the Companies to not apply the recognition requirements to short-term leases and an expedient that will allow the Companies to account for lease and associated non-lease components as a single lease component; (3) an expedient that allows the use of hindsight to determine lease term; and (4) an expedient that will allow the Companies to not evaluate under Topic 842 land easements that exist or expired before the entity’s adoption of Topic 842 and that were not previously accounted for as leases under the current lease standard. For leases currently classified as operating leases, upon adoption of the amendments, the Companies expect to recognize on their balance sheets right-of-use assets and lease liabilities. The adoption of the amendments is not expected to have a material effect on the Companies’ liquidity. The Companies are continuing to evaluate the potential impact of the amendments on the Companies’ results of operations and the additional disclosures required. The Companies will implement additional internal controls related to the amendments, however the adoption of the amendments is not expected to require a change that will materially affect the Companies’ internal control over financial reporting. In August 2017, the FASB issued amendments to the guidance for derivatives and hedging through ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” The amendments in this update provide greater clarification on hedge accounting for risk components, presentation and disclosure of hedging instruments, and overall targeted improvements to simplify hedge accounting. For public entities, the amendments are effective, and the Companies plan to adopt the amendments, for reporting periods beginning after December 15, 2018. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity. In February 2018, the FASB issued amendments to the guidance for reporting comprehensive income through ASU 2018-02, “Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” The amendments allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018, with early adoption permitted. The Companies are electing to adopt the amendments in the fourth quarter of 2018. The impact of adoption on the Companies’ financial position, results of operations and liquidity is expected to be immaterial. In August 2018, the FASB issued amendments to the guidance for internal use software through ASU 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract.” The amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019, with early adoption permitted. The Companies elected to adopt the amendments in the third quarter of 2018, prospectively for all in-scope implementation costs incurred after the date of adoption. The impact of adoption on the Companies’ financial position, results of operations and liquidity was immaterial.

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Disaggregation of Revenue



	For the Three Months Ended September 30, 2018					For the Nine Months Ended September 30, 2018
(Millions of Dollars)	Revenues from contracts with customers		Other revenues (a)		Total operating revenues	Revenues from contracts with customers		Other revenues (a)	Total operating revenues
CECONY
Electric	$2,631		$(60)		$2,571	$6,106		$1	$6,107
Gas	264		—		264	1,516		24	1,540
Steam	64		—		64	467		7	474
Total CECONY	$2,959		$(60)		$2,899	$8,089		$32	$8,121
O&R
Electric	215		(3)		212	508		(3)	505
Gas	31		3		34	179		7	186
Total O&R	$246			$—	$246	$687		$4	$691
Clean Energy Businesses
Renewables	68	(b)	—		68	273	(b)	—	273
Energy services	24		—		24	65		—	65
Other	—		89		89	—		235	235
Total Clean Energy Businesses	$92		$89		$181	$338		$235	$573
Con Edison Transmission	1		—		1	3		—	3
Other (c)	—		1		1	—		—	—
Total Con Edison	$3,298		$30		$3,328	$9,117		$271	$9,388


(c)	Parent company and consolidation adjustments.

Change in Unbilled Contract and Unearned Revenues



(Millions of Dollars)	Unbilled contract revenue (a)	Unearned revenue (b)
Beginning balance as of January 1, 2018	$58	$87
Additions (c)	111	34
Subtractions (c)	138	105	(d)
Ending balance as of September 30, 2018	$31	$16

(a)


(b)	Unearned revenue represents a liability for billings to customers in excess of earned revenue, which are contract liabilities as defined in Topic 606.


(c)	Additions for unbilled contract revenue and subtractions for unearned revenue represent additional revenue earned. Additions for unearned revenue and subtractions for unbilled contract revenue represent billings. Activity also includes appropriate balance sheet classification for the period.


(d)	Of the $105 million in subtractions from unearned revenue, $50 million was included in the balance as of December 31, 2017.

Basic and Diluted Earnings Per Share

For the three and nine months ended September 30, 2018 and 2017, basic and diluted EPS for Con Edison are calculated as follows:



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
(Millions of Dollars, except per share amounts/Shares in Millions)	2018	2017	2018	2017
Net income	$435	$457	$1,051	$1,020
Weighted average common shares outstanding – basic	311.1	307.8	310.8	306.2
Add: Incremental shares attributable to effect of potentially dilutive securities	1.2	1.5	1.1	1.5
Adjusted weighted average common shares outstanding – diluted	312.3	309.3	311.9	307.7
Net Income per common share – basic	$1.40	$1.48	$3.38	$3.33
Net Income per common share – diluted	$1.39	$1.48	$3.37	$3.31

Changes in Accumulated Other Comprehensive Income/(Loss)

For the three and nine months ended September 30, 2018 and 2017, changes to accumulated other comprehensive income/(loss) (OCI) for Con Edison and CECONY are as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Beginning balance, accumulated OCI, net of taxes (a)	$(20)	$(27)	$(5)	$(7)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(1) for Con Edison in 2018 and 2017 (a)(b)	2	1	—	1
Current period OCI, net of taxes	2	1	—	1
Ending balance, accumulated OCI, net of taxes	$(18)	$(26)	$(5)	$(6)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Beginning balance, accumulated OCI, net of taxes (a)	$(26)	$(27)	$(6)	$(7)
OCI before reclassifications, net of tax of $(1) and $1 for Con Edison in 2018 and 2017, respectively	3	(2)	—	—
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(2) for Con Edison in 2018 and 2017 (a)(b)	5	3	1	1
Current period OCI, net of taxes	8	1	1	1
Ending balance, accumulated OCI, net of taxes	$(18)	$(26)	$(5)	$(6)


(a)	Tax reclassified from accumulated OCI is reported in the income tax expense line item of the consolidated income statement.


(b)	For the portion of unrecognized pension and other postretirement benefit costs relating to the Utilities, costs are recorded into, and amortized out of, regulatory assets instead of OCI. The net actuarial losses and prior service costs recognized during the period are included in the computation of total periodic pension and other postretirement benefit cost. See Notes E and F.

Restrictions on Cash and Cash Equivalents

At September 30, 2018 and 2017, cash, temporary cash investments and restricted cash for Con Edison and CECONY are as follows:



	At September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Cash and temporary cash investments	$199	$69	$17	$17
Restricted cash (a)	46	41	—	—
Total cash, temporary cash investments and restricted cash	$245	$110	$17	$17

(a)

Schedule of Cash and Cash Equivalents

At September 30, 2018 and 2017, cash, temporary cash investments and restricted cash for Con Edison and CECONY are as follows:



	At September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Cash and temporary cash investments	$199	$69	$17	$17
Restricted cash (a)	46	41	—	—
Total cash, temporary cash investments and restricted cash	$245	$110	$17	$17

(a)

Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2018

Regulated Operations [Abstract]

Schedule of Regulatory Assets

Regulatory assets and liabilities at September 30, 2018 and December 31, 2017 were comprised of the following items:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Regulatory assets
Unrecognized pension and other postretirement costs	$2,001	$2,526	$1,881	$2,376
Environmental remediation costs	754	793	653	677
Revenue taxes	287	260	274	248
MTA power reliability deferral	189	50	189	50
Property tax reconciliation	85	51	68	25
Deferred storm costs	80	38	—	—
Pension and other postretirement benefits deferrals	73	79	56	58
Municipal infrastructure support costs	73	56	73	56
Recoverable energy costs	62	60	57	52
Unamortized loss on reacquired debt	37	37	36	35
Meadowlands heater odorization project	36	18	36	18
Brooklyn Queens demand management program	30	37	30	37
Preferred stock redemption	23	24	23	24
Deferred derivative losses	21	44	16	37
Gate station upgrade project	19	13	19	13
Recoverable REV demonstration project costs	18	19	16	17
Indian Point Energy Center program costs	15	29	15	29
Workers’ compensation	6	10	6	10
O&R transition bond charges	3	9	—	—
Other	138	113	128	101
Regulatory assets – noncurrent	3,950	4,266	3,576	3,863
Deferred derivative losses	19	40	14	37
Recoverable energy costs	6	27	5	25
Regulatory assets – current	25	67	19	62
Total Regulatory Assets	$3,975	$4,333	$3,595	$3,925
Regulatory liabilities
Future income tax	$2,547	$2,545	$2,389	$2,390
Allowance for cost of removal less salvage	878	846	745	719
TCJA net benefits*	325	—	304	—
Energy efficiency portfolio standard unencumbered funds	127	127	122	122
Pension and other postretirement benefit deferrals	120	207	97	181
Net unbilled revenue deferrals	86	183	86	183
Unrecognized other postretirement costs	78	92	78	92
Property tax reconciliation	57	107	57	107
Property tax refunds	45	44	45	44
Settlement of prudence proceeding	44	66	44	66
Earnings sharing - electric, gas and steam	25	29	16	19
Carrying charges on repair allowance and bonus depreciation	24	43	24	42
New York State income tax rate change	21	36	22	35
Settlement of gas proceedings	16	27	16	27
Base rate change deferrals	13	21	13	21
Variable-rate tax-exempt debt – cost rate reconciliation	7	30	6	26
Net utility plant reconciliations	7	12	4	8
Other	204	162	174	137
Regulatory liabilities – noncurrent	4,624	4,577	4,242	4,219
Revenue decoupling mechanism	56	29	55	21
Refundable energy costs	32	41	12	16
Deferred derivative gains	20	31	18	28
Regulatory liabilities – current	108	101	85	65
Total Regulatory Liabilities	$4,732	$4,678	$4,327	$4,284

* See "Other Regulatory Matters," above.

Schedule of Regulatory Liabilities

Regulatory assets and liabilities at September 30, 2018 and December 31, 2017 were comprised of the following items:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Regulatory assets
Unrecognized pension and other postretirement costs	$2,001	$2,526	$1,881	$2,376
Environmental remediation costs	754	793	653	677
Revenue taxes	287	260	274	248
MTA power reliability deferral	189	50	189	50
Property tax reconciliation	85	51	68	25
Deferred storm costs	80	38	—	—
Pension and other postretirement benefits deferrals	73	79	56	58
Municipal infrastructure support costs	73	56	73	56
Recoverable energy costs	62	60	57	52
Unamortized loss on reacquired debt	37	37	36	35
Meadowlands heater odorization project	36	18	36	18
Brooklyn Queens demand management program	30	37	30	37
Preferred stock redemption	23	24	23	24
Deferred derivative losses	21	44	16	37
Gate station upgrade project	19	13	19	13
Recoverable REV demonstration project costs	18	19	16	17
Indian Point Energy Center program costs	15	29	15	29
Workers’ compensation	6	10	6	10
O&R transition bond charges	3	9	—	—
Other	138	113	128	101
Regulatory assets – noncurrent	3,950	4,266	3,576	3,863
Deferred derivative losses	19	40	14	37
Recoverable energy costs	6	27	5	25
Regulatory assets – current	25	67	19	62
Total Regulatory Assets	$3,975	$4,333	$3,595	$3,925
Regulatory liabilities
Future income tax	$2,547	$2,545	$2,389	$2,390
Allowance for cost of removal less salvage	878	846	745	719
TCJA net benefits*	325	—	304	—
Energy efficiency portfolio standard unencumbered funds	127	127	122	122
Pension and other postretirement benefit deferrals	120	207	97	181
Net unbilled revenue deferrals	86	183	86	183
Unrecognized other postretirement costs	78	92	78	92
Property tax reconciliation	57	107	57	107
Property tax refunds	45	44	45	44
Settlement of prudence proceeding	44	66	44	66
Earnings sharing - electric, gas and steam	25	29	16	19
Carrying charges on repair allowance and bonus depreciation	24	43	24	42
New York State income tax rate change	21	36	22	35
Settlement of gas proceedings	16	27	16	27
Base rate change deferrals	13	21	13	21
Variable-rate tax-exempt debt – cost rate reconciliation	7	30	6	26
Net utility plant reconciliations	7	12	4	8
Other	204	162	174	137
Regulatory liabilities – noncurrent	4,624	4,577	4,242	4,219
Revenue decoupling mechanism	56	29	55	21
Refundable energy costs	32	41	12	16
Deferred derivative gains	20	31	18	28
Regulatory liabilities – current	108	101	85	65
Total Regulatory Liabilities	$4,732	$4,678	$4,327	$4,284

* See "Other Regulatory Matters," above.

Pension Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Total Periodic Benefit Costs

The components of the Companies’ total periodic benefit cost for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$72	$66	$68	$61
Interest cost on projected benefit obligation	140	148	131	139
Expected return on plan assets	(258)	(243)	(245)	(229)
Recognition of net actuarial loss	172	149	163	141
Recognition of prior service cost/(credit)	(4)	(4)	(5)	(5)
TOTAL PERIODIC BENEFIT COST	$122	$116	$112	$107
Cost capitalized	(32)	(40)	(30)	(37)
Reconciliation to rate level	(22)	(14)	(24)	(16)
Total expense recognized	$68	$62	$58	$54



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$218	$197	$204	$184
Interest cost on projected benefit obligation	420	444	394	416
Expected return on plan assets	(775)	(726)	(734)	(689)
Recognition of net actuarial loss	516	446	488	423
Recognition of prior service cost/(credit)	(13)	(13)	(15)	(14)
TOTAL PERIODIC BENEFIT COST	$366	$348	$337	$320
Cost capitalized	(94)	(134)	(89)	(125)
Reconciliation to rate level	(68)	(28)	(74)	(32)
Total expense recognized	$204	$186	$174	$163

The components of the Companies’ total periodic other postretirement benefit cost/(credit) for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$5	$5	$3	$3
Interest cost on accumulated other postretirement benefit obligation	11	11	9	9
Expected return on plan assets	(18)	(17)	(16)	(15)
Recognition of net actuarial loss/(gain)	2	1	1	—
Recognition of prior service cost/(credit)	(2)	(5)	(1)	(3)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(2)	$(5)	$(4)	$(6)
Cost capitalized	(2)	2	(1)	2
Reconciliation to rate level	2	(1)	2	—
Total expense/(credit) recognized	$(2)	$(4)	$(3)	$(4)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$15	$15	$10	$10
Interest cost on accumulated other postretirement benefit obligation	32	34	26	28
Expected return on plan assets	(55)	(52)	(47)	(45)
Recognition of net actuarial loss/(gain)	6	2	2	(2)
Recognition of prior service cost/(credit)	(5)	(13)	(2)	(9)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(7)	$(14)	$(11)	$(18)
Cost capitalized	(6)	6	(4)	7
Reconciliation to rate level	6	(3)	7	(1)
Total expense/(credit) recognized	$(7)	$(11)	$(8)	$(12)

Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Total Periodic Benefit Costs

The components of the Companies’ total periodic benefit cost for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$72	$66	$68	$61
Interest cost on projected benefit obligation	140	148	131	139
Expected return on plan assets	(258)	(243)	(245)	(229)
Recognition of net actuarial loss	172	149	163	141
Recognition of prior service cost/(credit)	(4)	(4)	(5)	(5)
TOTAL PERIODIC BENEFIT COST	$122	$116	$112	$107
Cost capitalized	(32)	(40)	(30)	(37)
Reconciliation to rate level	(22)	(14)	(24)	(16)
Total expense recognized	$68	$62	$58	$54



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost – including administrative expenses	$218	$197	$204	$184
Interest cost on projected benefit obligation	420	444	394	416
Expected return on plan assets	(775)	(726)	(734)	(689)
Recognition of net actuarial loss	516	446	488	423
Recognition of prior service cost/(credit)	(13)	(13)	(15)	(14)
TOTAL PERIODIC BENEFIT COST	$366	$348	$337	$320
Cost capitalized	(94)	(134)	(89)	(125)
Reconciliation to rate level	(68)	(28)	(74)	(32)
Total expense recognized	$204	$186	$174	$163

The components of the Companies’ total periodic other postretirement benefit cost/(credit) for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$5	$5	$3	$3
Interest cost on accumulated other postretirement benefit obligation	11	11	9	9
Expected return on plan assets	(18)	(17)	(16)	(15)
Recognition of net actuarial loss/(gain)	2	1	1	—
Recognition of prior service cost/(credit)	(2)	(5)	(1)	(3)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(2)	$(5)	$(4)	$(6)
Cost capitalized	(2)	2	(1)	2
Reconciliation to rate level	2	(1)	2	—
Total expense/(credit) recognized	$(2)	$(4)	$(3)	$(4)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Service cost	$15	$15	$10	$10
Interest cost on accumulated other postretirement benefit obligation	32	34	26	28
Expected return on plan assets	(55)	(52)	(47)	(45)
Recognition of net actuarial loss/(gain)	6	2	2	(2)
Recognition of prior service cost/(credit)	(5)	(13)	(2)	(9)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	$(7)	$(14)	$(11)	$(18)
Cost capitalized	(6)	6	(4)	7
Reconciliation to rate level	6	(3)	7	(1)
Total expense/(credit) recognized	$(7)	$(11)	$(8)	$(12)

Environmental Matters (Tables)

9 Months Ended

Sep. 30, 2018

Environmental Remediation Obligations [Abstract]

Accrued Liabilities and Regulatory Assets

The accrued liabilities and regulatory assets related to Superfund Sites at September 30, 2018 and December 31, 2017 were as follows:



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Accrued Liabilities:
Manufactured gas plant sites	$639	$651	$546	$551
Other Superfund Sites	81	86	80	86
Total	$720	$737	$626	$637
Regulatory assets	$754	$793	$653	$677

Environmental Remediation Costs

Environmental remediation costs incurred related to Superfund Sites for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Remediation costs incurred	$8	$4	$5	$3



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Remediation costs incurred	$17	$18	$14	$13

Accrued Liability for Asbestos Suits and Workers' Compensation Proceedings



	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018	2017
Accrued liability – asbestos suits	$8	$8	$7	$7
Regulatory assets – asbestos suits	$8	$8	$7	$7
Accrued liability – workers’ compensation	$80	$84	$76	$80
Regulatory assets – workers’ compensation	$6	$10	$6	$10

Other Material Contingencies (Tables)

9 Months Ended

Sep. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

Summary of Total Guarantees

A summary, by type and term, of Con Edison’s total guarantees under these other agreements at September 30, 2018 is as follows:



Guarantee Type	0 – 3 years	4 – 10 years	> 10 years		Total
	(Millions of Dollars)
Con Edison Transmission	$744	$404		$—	$1,148
Energy transactions	434	24	201		659
Renewable electric production projects	93	—	21		114
Other	70	—	—		70
Total	$1,341	$428	$222		$1,991

Income Tax (Tables)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Schedule of Income Tax Reconciliation



	Con Edison				CECONY
(% of Pre-tax income)	2018		2017		2018		2017
STATUTORY TAX RATE
Federal	21	%	35	%	21	%	35	%
Changes in computed taxes resulting from:
State income tax	5		4		5		4
Cost of removal	1		1		1		1
Other plant-related items	(1	)	(1	)	(1	)	(1	)
Renewable energy credits	(1	)	(1	)	—		—
TCJA deferred tax re-measurement	3		—		—		—
Amortization of excess deferred federal income taxes	(3	)	—		(3	)	—
Other	(1	)	(1	)	(1	)	(1	)
Effective tax rate	24	%	37	%	22	%	38	%



	Con Edison				CECONY
(% of Pre-tax income)	2018		2017		2018		2017
STATUTORY TAX RATE
Federal	21	%	35	%	21	%	35	%
Changes in computed taxes resulting from:
State income tax	5		5		5		4
Other plant-related items	(1	)	(1	)	(1	)	(1	)
Renewable energy credits	(1	)	(1	)	—		—
TCJA deferred tax re-measurement	7		—		—		—
Amortization of excess deferred federal income taxes	(2	)	—		(2	)	—
Other	(1	)	(1	)	(1	)	—
Effective tax rate	28	%	37	%	22	%	38	%

Financial Information by Business Segment (Tables)

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Financial Data for Business Segments

The financial data for the business segments for the three and nine months ended September 30, 2018 and 2017 were as follows:



	For the Three Months Ended September 30,
	Operating revenues		Inter-segment revenues				Depreciation and amortization		Operating income/(loss)
(Millions of Dollars)	2018	2017	2018		2017		2018	2017	2018	2017
CECONY
Electric	$2,571	$2,469	$4		$4		$248	$232	$850	$883
Gas	264	268	2		2		52	47	(34)	(6)
Steam	64	62	19		19		22	21	(52)	(41)
Consolidation adjustments	—	—	(25)		(25)		—	—	—	—
Total CECONY	$2,899	$2,799		$—		$—	$322	$300	$764	$836
O&R
Electric	$212	$206		$—		$—	$14	$13	$52	$60
Gas	34	28	—		—		5	5	(10)	(10)
Total O&R	$246	$234		$—		$—	$19	$18	$42	$50
Clean Energy Businesses	$181	$177		$—		$—	$18	$19	$25	$29
Con Edison Transmission	1	1	—		—		—	—	(2)	(2)
Other (a)	1	—	—		—		1	—	(3)	1
Total Con Edison	$3,328	$3,211		$—		$—	$360	$337	$826	$914



	For the Nine Months Ended September 30,
	Operating revenues		Inter-segment revenues				Depreciation and amortization		Operating income/(loss)
(Millions of Dollars)	2018	2017	2018		2017		2018	2017	2018	2017
CECONY
Electric	$6,107	$6,079	$12		$12		$732	$690	$1,421	$1,561
Gas	1,540	1,421	6		5		152	137	369	379
Steam	474	448	56		55		65	64	60	59
Consolidation adjustments	—	—	(74)		(72)		—	—	—	—
Total CECONY	$8,121	$7,948		$—		$—	$949	$891	$1,850	$1,999
O&R
Electric	$505	$495		$—		$—	$41	$38	$79	$94
Gas	186	172	—		—		16	15	31	37
Total O&R	$691	$667		$—		$—	$57	$53	$110	$131
Clean Energy Businesses	573	460	—		—		55	54	59	63
Con Edison Transmission	3	1	—		—		1	—	(5)	(6)
Other (a)	—	(4)	—		—		(1)	—	(7)	2
Total Con Edison	$9,388	$9,072		$—		$—	$1,061	$998	$2,007	$2,189

(a) Parent company and consolidation adjustments. Other does not represent a business segment.

Derivative Instruments and Hedging Activities (Tables)

9 Months Ended

Sep. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Offsetting of Liabilities

The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2018 and December 31, 2017 were:



(Millions of Dollars)	2018					2017
Balance Sheet Location	Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)		Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)
Con Edison
Fair value of derivative assets
Current	$45	$(23)		$22	(b)	$83	$(51)		$32	(b)
Noncurrent	21	(13)		8		10	(4)		6
Total fair value of derivative assets	$66	$(36)		$30		$93	$(55)		$38
Fair value of derivative liabilities
Current	$(41)	$23		$(18)		$(67)	$50		$(17)
Noncurrent	(26)	13		(13)		(43)	5		(38)
Total fair value of derivative liabilities	$(67)	$36		$(31)		$(110)	$55		$(55)
Net fair value derivative assets/(liabilities)	$(1)		$—	$(1)	(b)	$(17)		$—	$(17)	(b)
CECONY
Fair value of derivative assets
Current	$32	$(16)		$16	(b)	$39	$(15)		$24	(b)
Noncurrent	16	(11)		5		9	(4)		5
Total fair value of derivative assets	$48	$(27)		$21		$48	$(19)		$29
Fair value of derivative liabilities
Current	$(19)	$15		$(4)		$(26)	$14		$(12)
Noncurrent	(20)	11		(9)		(36)	4		(32)
Total fair value of derivative liabilities	$(39)	$26		$(13)		$(62)	$18		$(44)
Net fair value derivative assets/(liabilities)	$9	$(1)		$8	(b)	$(14)	$(1)		$(15)	(b)

(a)

(b)

Offsetting of Assets

The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2018 and December 31, 2017 were:



(Millions of Dollars)	2018					2017
Balance Sheet Location	Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)		Gross Amounts of Recognized Assets/(Liabilities)	Gross Amounts Offset		Net Amounts of Assets/ (Liabilities) (a)
Con Edison
Fair value of derivative assets
Current	$45	$(23)		$22	(b)	$83	$(51)		$32	(b)
Noncurrent	21	(13)		8		10	(4)		6
Total fair value of derivative assets	$66	$(36)		$30		$93	$(55)		$38
Fair value of derivative liabilities
Current	$(41)	$23		$(18)		$(67)	$50		$(17)
Noncurrent	(26)	13		(13)		(43)	5		(38)
Total fair value of derivative liabilities	$(67)	$36		$(31)		$(110)	$55		$(55)
Net fair value derivative assets/(liabilities)	$(1)		$—	$(1)	(b)	$(17)		$—	$(17)	(b)
CECONY
Fair value of derivative assets
Current	$32	$(16)		$16	(b)	$39	$(15)		$24	(b)
Noncurrent	16	(11)		5		9	(4)		5
Total fair value of derivative assets	$48	$(27)		$21		$48	$(19)		$29
Fair value of derivative liabilities
Current	$(19)	$15		$(4)		$(26)	$14		$(12)
Noncurrent	(20)	11		(9)		(36)	4		(32)
Total fair value of derivative liabilities	$(39)	$26		$(13)		$(62)	$18		$(44)
Net fair value derivative assets/(liabilities)	$9	$(1)		$8	(b)	$(14)	$(1)		$(15)	(b)

(a)

(b)

Realized and Unrealized Gains or Losses on Commodity Derivatives



		For the Three Months Ended September 30,
		Con Edison						CECONY
(Millions of Dollars)	Balance Sheet Location	2018			2017			2018		2017
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Current	Deferred derivative gains	$6			$(4)			$6		$(3)
Noncurrent	Deferred derivative gains	—			1			2		1
Total deferred gains/(losses)		$6			$(3)			$8		$(2)
Current	Deferred derivative losses	$25			$(11)			$25		$(9)
Current	Recoverable energy costs	(4)			(40)			(6)		(38)
Noncurrent	Deferred derivative losses	15			(12)			14		(8)
Total deferred gains/(losses)		$36			$(63)			$33		$(55)
Net deferred gains/(losses)		$42			$(66)			$41		$(57)
	Income Statement Location
Pre-tax gains/(losses) recognized in income
	Purchased power expense		$—			$—			$—		$—
	Gas purchased for resale	—			(47)			—		—
	Non-utility revenue	(7)		(a)	5		(b)	—		—
Total pre-tax gains/(losses) recognized in income		$(7)			$(42)				$—		$—


(a)	For the three months ended September 30, 2018, Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ($4 million).


(b)	For the three months ended September 30, 2017, Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ($6 million).



		For the Nine Months Ended September 30,
		Con Edison						CECONY
(Millions of Dollars)	Balance Sheet Location	2018			2017			2018		2017
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Current	Deferred derivative gains	$(11)			$(26)			$(10)		$(22)
Noncurrent	Deferred derivative gains	5			(2)			4		(2)
Total deferred gains/(losses)		$(6)			$(28)			$(6)		$(24)
Current	Deferred derivative losses	$21			$10			$23		$11
Current	Recoverable energy costs	(13)			(125)			(14)		(116)
Noncurrent	Deferred derivative losses	23			(40)			21		(36)
Total deferred gains/(losses)		$31			$(155)			$30		$(141)
Net deferred gains/(losses)		$25			$(183)			$24		$(165)
	Income Statement Location
Pre-tax gains/(losses) recognized in income
	Purchased power expense		$—			$—			$—		$—
	Gas purchased for resale	(1)			(161)			—		—
	Non-utility revenue	(7)		(a)	11		(b)	—		—
Total pre-tax gains/(losses) recognized in income		$(8)			$(150)				$—		$—


(a)	For the nine months ended September 30, 2018, Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ($6 million).


(b)	For the nine months ended September 30, 2017, Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ($2 million

Hedged Volume of Derivative Transactions

The following table presents the hedged volume of Con Edison’s and CECONY’s derivative transactions at September 30, 2018:



	Electric Energy (MWh) (a)(b)	Capacity (MW) (a)	Natural Gas (Dt) (a)(b)	Refined Fuels (gallons)
Con Edison	30,590,984	8,134	195,821,882	2,688,000
CECONY	27,983,800	3,300	182,820,000	2,688,000


(a)	Volumes are reported net of long and short positions, except natural gas collars where the volumes of long positions are reported.


(b)	Excludes electric congestion and gas basis swap contracts, which are associated with electric and gas contracts and hedged volumes.

Aggregate Fair Value of Companies' Derivative Instruments with Credit-Risk-Related Contingent Features



(Millions of Dollars)	Con Edison (a)		CECONY (a)
Aggregate fair value – net liabilities	$19		$9
Collateral posted	13		10
Additional collateral (b) (downgrade one level from current ratings)	—		—
Additional collateral (b) (downgrade to below investment grade from current ratings)	17	(c)	7	(c)

(a)

(b)


(c)	Derivative instruments that are net assets have been excluded from the table. At September 30, 2018, if Con Edison had been downgraded to below investment grade, it would have been required to post additional collateral for such derivative instruments of $22 million.

- Definition

Tabular disclosure of credit derivatives which includes information by sellers of credit derivatives, about each credit derivative, or each group of similar credit derivatives, including (a) the nature of the credit derivative - its term, how it arose, the events or circumstances that would require the seller to perform under the credit derivative, and the current status of the payment/performance risk of the credit derivative; (b) the maximum potential amount of future payments (undiscounted) the seller could be required to make under the credit derivative; (c) the current fair value of the credit derivative; and (d) the nature of any recourse provisions under the credit derivative, and any assets held either as collateral or by third parties. A credit derivative is a derivative instrument (1) in which one or more of its underlyings are related to the credit risk of a specified entity (or a group of entities) or an index based on the credit risk of a group of entities and (2) that exposes the seller to potential loss from credit-risk-related events specified in the contract. Examples of credit derivatives within the scope of this paragraph include, but are not limited to, credit default swaps, credit spread options, and credit index products; also includes a hybrid instrument that has an embedded credit derivative (for example, but not limited to, a credit-linked note).

+ References + Details

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

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+ Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 are summarized below.



	2018					2017
(Millions of Dollars)	Level 1	Level 2	Level 3	Netting Adjustment (e)	Total	Level 1	Level 2	Level 3		Netting Adjustment (e)	Total
Con Edison
Derivative assets:
Commodity (a)(b)(c)	$3	$40	$8	$(14)	$37	$5	$77	$7		$(39)	$50
Interest rate swap (a)(b)(c)	—	1	—	—	1	—	—	—		—	—
Other (a)(b)(d)	314	119	—	—	433	283	120	—		—	403
Total assets	$317	$160	$8	$(14)	$471	$288	$197	$7		$(39)	$453
Derivative liabilities:
Commodity (a)(b)(c)	$5	$30	$18	$(22)	$31	$8	$93	$6		$(52)	$55
CECONY
Derivative assets:
Commodity (a)(b)(c)	$3	$33	$1	$(10)	$27	$3	$40	$4		$(7)	$40
Other (a)(b)(d)	293	113	—	—	406	260	114	—		—	374
Total assets	$296	$146	$1	$(10)	$433	$263	$154	$4		$(7)	$414
Derivative liabilities:
Commodity (a)(b)(c)	$4	$22	$1	$(14)	$13	$5	$57		$—	$(18)	$44

(a)

(b)

(c)


(d)	Other assets are comprised of assets such as life insurance contracts within the deferred compensation plan and non-qualified retirement plans.


(e)	Amounts represent the impact of legally-enforceable master netting agreements that allow the Companies to net gain and loss positions and cash collateral held or placed with the same counterparties.

Schedule of Commodity Derivatives



	Fair Value of Level 3 at September 30, 2018		Valuation Techniques	Unobservable Inputs	Range
	(Millions of Dollars)		Valuation Techniques	Unobservable Inputs	Range
Con Edison – Commodity
Electricity	$(7)		Discounted Cash Flow	Forward energy prices (a)	$18.33-$79.20 per MWh
			Discounted Cash Flow	Forward capacity prices (a)	$1.70-$8.84 per kW-month
Natural Gas	(4)		Discounted Cash Flow	Forward natural gas prices (a)	$0.96-$10.51 per Dt
Transmission Congestion Contracts/Financial Transmission Rights	1		Discounted Cash Flow	Inter-zonal forward price curves adjusted for historical zonal losses (b)	$0.37-$5.45 per MWh
Total Con Edison—Commodity	$(10)
CECONY – Commodity
Electricity	$(1)		Discounted Cash Flow	Forward capacity prices (a)	$1.70-$7.20 per kW-month
Transmission Congestion Contracts	1		Discounted Cash Flow	Inter-zonal forward price curves adjusted for historical zonal losses (b)	$0.45-$4.18 per MWh
Total CECONY—Commodity		$—


(a)	Generally, increases/(decreases) in this input in isolation would result in a higher/(lower) fair value measurement.


(b)	Generally, increases/(decreases) in this input in isolation would result in a lower/(higher) fair value measurement.

Reconciliation of Beginning and Ending Net Balances for Assets and Liabilities Measured at Level 3 Fair Value



	For the Three Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018		2017
Beginning balance as of July 1,	$(4)	$(10)		$—	$(6)
Included in earnings	4	7	2		1
Included in regulatory assets and liabilities	(4)	(13)	—		(8)
Settlements	(6)	(4)	(2)		(1)
Ending balance as of September 30,	$(10)	$(20)		$—	$(14)



	For the Nine Months Ended September 30,
	Con Edison		CECONY
(Millions of Dollars)	2018	2017	2018		2017
Beginning balance as of January 1,	$1	$1	$4		$1
Included in earnings	4	8	4		1
Included in regulatory assets and liabilities	(7)	(21)	(5)		(14)
Purchases	—	1	—		1
Settlements	(9)	(9)	(4)		(3)
Transfer out of level 3	1	—	1		—
Ending balance as of September 30,	$(10)	$(20)		$—	$(14)

Variable Interest Entities (Tables)

9 Months Ended

Sep. 30, 2018

Equity Method Investments and Joint Ventures [Abstract]

Summary of VIEs

The following table summarizes the VIEs in which Con Edison Development has entered into as of September 30, 2018:



Project Name (a)	Generating Capacity (b) (MW AC)	Power Purchase Agreement Term (in Years)	Year of Initial Investment	Location	Maximum Exposure to Loss (Millions of Dollars) (c)
Copper Mountain Solar 3 (d)	128	20	2014	Nevada	$169
Mesquite Solar 1 (d)	83	20	2013	Arizona	101
Copper Mountain Solar 2 (d)	75	25	2013	Nevada	80
California Solar (d)	55	25	2012	California	59
Broken Bow II (d)	38	25	2014	Nebraska	42
Texas Solar 4	32	25	2014	Texas	19

(b) Represents Con Edison Development’s ownership interest in the project.


(d)	In September 2018, a Con Edison Development subsidiary agreed to purchase Sempra Solar Holdings, LLC, subsidiaries of which have a 50 percent ownership interest in these projects. Upon the closing of the acquisition, Con Edison expects to account for these projects on a consolidated basis. See Note O.

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References + Details

General (Details)	9 Months Ended
General (Details)	Sep. 30, 2018 subsidiary registrant
Accounting Policies [Abstract]
Number of registrants \| registrant	2
Number of regulated utility subsidiaries	2
Clean Energy Businesses
Investment [Line Items]
Number of subsidiaries	3

Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,298		$ 9,117
Total revenues	3,328	$ 3,211	9,388	$ 9,072
Other
Disaggregation of Revenue [Line Items]
Total revenues	30		271
Clean Energy Businesses \| Renewables \| Engineering, procurement and construction
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3		100
CECONY
Disaggregation of Revenue [Line Items]
Total revenues	2,899	2,799	8,121	7,948
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	3,328	3,211	9,388	9,072
Operating Segments \| Clean Energy Businesses
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	92		338
Total revenues	181	177	573	460
Operating Segments \| Clean Energy Businesses \| Other
Disaggregation of Revenue [Line Items]
Total revenues	89		235
Operating Segments \| Clean Energy Businesses \| Renewables
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	68		273
Total revenues	68		273
Operating Segments \| Clean Energy Businesses \| Renewables \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		0
Operating Segments \| Clean Energy Businesses \| Energy services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	24		65
Total revenues	24		65
Operating Segments \| Clean Energy Businesses \| Energy services \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		0
Operating Segments \| Clean Energy Businesses \| Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Total revenues	89		235
Operating Segments \| Clean Energy Businesses \| Other \| Other
Disaggregation of Revenue [Line Items]
Total revenues	89		235
Operating Segments \| Con Edison Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1		3
Total revenues	1	1	3	1
Operating Segments \| Con Edison Transmission \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		0
Operating Segments \| CECONY
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,959		8,089
Total revenues	2,899	2,799	8,121	7,948
Operating Segments \| CECONY \| Other
Disaggregation of Revenue [Line Items]
Total revenues	(60)		32
Operating Segments \| CECONY \| Electric
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,631		6,106
Total revenues	2,571	2,469	6,107	6,079
Operating Segments \| CECONY \| Electric \| Other
Disaggregation of Revenue [Line Items]
Total revenues	(60)		1
Operating Segments \| CECONY \| Gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	264		1,516
Total revenues	264	268	1,540	1,421
Operating Segments \| CECONY \| Gas \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		24
Operating Segments \| CECONY \| Steam
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	64		467
Total revenues	64	62	474	448
Operating Segments \| CECONY \| Steam \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		7
Operating Segments \| O&R
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	246		687
Total revenues	246	234	691	667
Operating Segments \| O&R \| Other
Disaggregation of Revenue [Line Items]
Total revenues	0		4
Operating Segments \| O&R \| Electric
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	215		508
Total revenues	212	206	505	495
Operating Segments \| O&R \| Electric \| Other
Disaggregation of Revenue [Line Items]
Total revenues	(3)		(3)
Operating Segments \| O&R \| Gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	31		179
Total revenues	34	28	186	172
Operating Segments \| O&R \| Gas \| Other
Disaggregation of Revenue [Line Items]
Total revenues	3		7
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Total revenues	1	$ 0	0	$ (4)
Other \| Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 1		$ 0

Summary of Significant Accounting Policies - Change in Unbilled Contract and Unearned Revenues (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Unbilled contract revenue
Beginning balance	$ 58
Additions	111
Subtractions	138
Ending balance	31	$ 58
Unearned revenue
Beginning balance	87
Additions	34
Subtractions	105
Ending balance	$ 16	87
Contracts with customer, revenue recognized, amount outstanding end of last period		$ 50

Summary of Significant Accounting Policies - Revenue Recognition, Remaining Performance Obligation (Details) $ in Millions	Sep. 30, 2018 USD ($)
Accounting Policies [Abstract]
Remaining performance obligation	$ 124
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Accounting Policies [Abstract]
Remaining performance obligation	$ 87
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Accounting Policies [Abstract]
Remaining performance obligation	$ 37
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction

Summary of Significant Accounting Policies - Utility Plant (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 21	$ 15
Software Licenses
Finite-Lived Intangible Assets [Line Items]
Gross asset	$ 102
Amortization period	15 years
Estimated aggregate annual amortization expense	$ 7
Accumulated amortization	2
Software Licenses \| CECONY
Finite-Lived Intangible Assets [Line Items]
Gross asset	97
Estimated aggregate annual amortization expense	7
Accumulated amortization	$ 1

Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Net income	$ 435	$ 457	$ 1,051	$ 1,020
Weighted average common shares outstanding – basic	311.1	307.8	310.8	306.2
Add: Incremental shares attributable to effect of potentially dilutive securities	1.2	1.5	1.1	1.5
Adjusted weighted average common shares outstanding – diluted	312.3	309.3	311.9	307.7
Net income per common share - basic (dollars per share)	$ 1.40	$ 1.48	$ 3.38	$ 3.33
Net income per common share - diluted (dollars per share)	$ 1.39	$ 1.48	$ 3.37	$ 3.31

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			$ 15,425
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	$ 2	$ 1	8	$ 1
Ending Balance	15,898		15,898
Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(20)	(27)	(26)	(27)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES			8
Ending Balance	(18)	(26)	(18)	(26)
Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax of $(1) and $1 for Con Edison in 2018 and 2017, respectively			3	(2)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	2	1	5	3
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	2	1	8	1
OCI before reclassifications, tax			(1)	1
Amounts reclassified from accumulated OCI related to pension plan liabilities, tax	(1)	(1)	(2)	(2)
CECONY
AOCI Attributable to Parent, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	0	1	1	1
CECONY \| Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(5)	(7)	(6)	(7)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES			1
Ending Balance	(5)	(6)	(5)	(6)
CECONY \| Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax of $(1) and $1 for Con Edison in 2018 and 2017, respectively			0	0
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	0	1	1	1
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	$ 0	$ 1	$ 1	$ 1

Summary of Significant Accounting Policies - Reconciliation of Cash, Temporary Investments and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and temporary cash investments	$ 199	$ 797	$ 69
Restricted cash	46		41
Total cash, temporary cash investments and restricted cash	245	844	110	$ 830
CEB \| Cash Collateral Held for Project Finance Agreements
Cash and Cash Equivalents [Line Items]
Restricted cash	44		39
CECONY
Cash and Cash Equivalents [Line Items]
Cash and temporary cash investments	17	730	17
Restricted cash	0		0
Total cash, temporary cash investments and restricted cash	17	$ 730	17	$ 704
RECO \| Transition Bond
Cash and Cash Equivalents [Line Items]
Restricted cash	$ 2		$ 2

Regulatory Matters - Rate Plans (Details) - O&R - NYSPSC - USD ($) $ in Millions	1 Months Ended
	Jun. 30, 2018	May 31, 2018
Electric
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ 10.6
Increase (decrease) in requested rate increase	$ 30.4
Authorized return on common equity, percentage	9.75%	8.60%
Gas
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ (6.7)
Increase (decrease) in requested rate increase	$ (0.5)
Authorized return on common equity, percentage	9.75%	8.60%

Regulatory Matters - Other Regulatory Matters (Details) customer in Thousands, $ in Millions		1 Months Ended				3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2018 USD ($)	Sep. 30, 2018 USD ($)	Aug. 31, 2018 USD ($)	Mar. 31, 2018 USD ($) customer	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets		$ 3,975.0			$ 4,333.0			$ 3,975.0	$ 3,975.0
Utilities
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									325.0
CECONY
Public Utilities, General Disclosures [Line Items]
Regulatory assets		3,595.0			3,925.0			3,595.0	3,595.0
CECONY \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA		51.0			3,513.0
CECONY \| Accelerated Tax Depreciation Benefits
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									2,593.0
CECONY \| Deferred Income Tax Charge, Amortized Over Remaining Life of Asset
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									971.0
CECONY \| Electric \| Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service \| customer				209
Restoration costs								125.0
Operation and maintenance expenses								16.0
Operation and maintenance expenses charged against a storm reserve								76.0
Capital expenditures		27.0						27.0	27.0
Removal costs								6.0
O&R \| Future Income Tax
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA		7.0			$ 161.0
O&R \| Accelerated Tax Depreciation Benefits
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									133.0
O&R \| Deferred Income Tax Charge, Amortized Over Remaining Life of Asset
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									35.0
O&R \| Electric \| Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service \| customer				93
Restoration costs								44.0
RECO \| Electric \| Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers affected with interrupted service \| customer				44
Restoration costs								17.0
NYSPSC \| CECONY \| Electric
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA			$ 2,514.0
NYSPSC \| CECONY \| Gas
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									808.0
NYSPSC \| CECONY \| Steam
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA									190.0
Income tax benefit to be credited to customers resulting from TCJA									$ 15.0
Tax credit, amortization period									3 years
NYSPSC \| CECONY \| Scenario, Forecast \| Electric
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						$ 304.0				$ 247.0
NYSPSC \| CECONY \| Scenario, Forecast \| Gas
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						82.0				102.0
NYSPSC \| CECONY \| Scenario, Forecast \| Steam
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						6.0				$ 25.0
NYSPSC \| CECONY \| MTA Subway Power Outage
Public Utilities, General Disclosures [Line Items]
Regulatory costs		219.0						219.0	$ 219.0
Regulatory assets		189.0						189.0	189.0
NYSPSC \| CECONY \| MTA Subway Power Outage \| Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Regulatory costs						51.0
NYSPSC \| CECONY \| MTA Subway Power Outage \| Electric
Public Utilities, General Disclosures [Line Items]
Regulatory costs		$ 30.0						$ 30.0	$ 30.0
NYSPSC \| O&R \| Scenario, Forecast \| Electric and Gas
Public Utilities, General Disclosures [Line Items]
Income tax benefit to be credited to customers resulting from TCJA						$ 22.0
Tax credit, amortization period						3 years
NJBPU \| RECO \| Electric
Public Utilities, General Disclosures [Line Items]
Approved interim rate decrease	$ 2.9
Net benefit of the TCJA							$ 1.0
FERC \| RECO
Public Utilities, General Disclosures [Line Items]
Impact in regulatory liability resulting from TCJA				$ 28.0
Impact in regulatory liability resulting from TCJA, subject to normalization requirements				$ 16.0

Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 3,950	$ 4,266
Regulatory assets – current	25	67
Total Regulatory Assets	3,975	4,333
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,001	2,526
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	754	793
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	287	260
MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	189	50
Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	85	51
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	80	38
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	73	79
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	73	56
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	62	60
Regulatory assets – current	6	27
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	37	37
Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	36	18
Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	30	37
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	24
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	21	44
Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	19	13
Recoverable REV demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	19
Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	15	29
Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	6	10
O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	3	9
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	138	113
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	19	40
CECONY
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	3,576	3,863
Regulatory assets – current	19	62
Total Regulatory Assets	3,595	3,925
CECONY \| Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	1,881	2,376
CECONY \| Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	653	677
CECONY \| Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	274	248
CECONY \| MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	189	50
CECONY \| Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	68	25
CECONY \| Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY \| Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	56	58
CECONY \| Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	73	56
CECONY \| Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	57	52
Regulatory assets – current	5	25
CECONY \| Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	36	35
CECONY \| Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	36	18
CECONY \| Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	30	37
CECONY \| Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	24
CECONY \| Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	16	37
CECONY \| Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	19	13
CECONY \| Recoverable REV demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	16	17
CECONY \| Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	15	29
CECONY \| Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	6	10
CECONY \| O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY \| Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	128	101
CECONY \| Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	$ 14	$ 37

Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 4,624	$ 4,577
Regulatory liabilities – current	108	101
Total Regulatory Liabilities	4,732	4,678
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	2,547	2,545
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	878	846
TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent		0
Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	127	127
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	120	207
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	86	183
Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	78	92
Property tax reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	57	107
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	45	44
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	44	66
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	25	29
Carrying charges on repair allowance and bonus depreciation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24	43
New York State income tax rate change
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	21	36
Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	16	27
Base rate change deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	21
Variable-rate tax-exempt debt – cost rate reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	7	30
Net utility plant reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	7	12
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	204	162
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	56	29
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	32	41
Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	20	31
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,242	4,219
Regulatory liabilities – current	85	65
Total Regulatory Liabilities	4,327	4,284
CECONY \| Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	2,389	2,390
CECONY \| Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	745	719
CECONY \| TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	304	0
CECONY \| Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	122	122
CECONY \| Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	97	181
CECONY \| Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	86	183
CECONY \| Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	78	92
CECONY \| Property tax reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	57	107
CECONY \| Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	45	44
CECONY \| Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	44	66
CECONY \| Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	16	19
CECONY \| Carrying charges on repair allowance and bonus depreciation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24	42
CECONY \| New York State income tax rate change
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	22	35
CECONY \| Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	16	27
CECONY \| Base rate change deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	21
CECONY \| Variable-rate tax-exempt debt – cost rate reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	26
CECONY \| Net utility plant reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4	8
CECONY \| Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	174	137
CECONY \| Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	55	21
CECONY \| Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	12	16
CECONY \| Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 18	$ 28

Capitalization - Additional Information (Details) - USD ($)	1 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Apr. 30, 2018	Dec. 31, 2018	Aug. 31, 2018	May 31, 2018
CECONY
Schedule of Capitalization [Line Items]
Tax-exempt debt		$ 636,000,000
CECONY \| Debentures \| 5.85% Debentures
Schedule of Capitalization [Line Items]
Face amount of debt			$ 600,000,000
Interest rate			5.85%
Debt term			10 years
CECONY \| Debentures \| 3.80% Debentures
Schedule of Capitalization [Line Items]
Face amount of debt						$ 300,000,000
Interest rate						3.80%
CECONY \| Debentures \| 4.50% Debentures
Schedule of Capitalization [Line Items]
Face amount of debt						$ 700,000,000
Interest rate						4.50%
CECONY \| Debentures \| Floating Rate Debentures
Schedule of Capitalization [Line Items]
Face amount of debt		$ 640,000,000
O&R \| Debentures \| 4.35% Debentures
Schedule of Capitalization [Line Items]
Face amount of debt					$ 125,000,000
Interest rate					4.35%
O&R \| Debentures \| 4.35% Debentures \| Scenario, Forecast
Schedule of Capitalization [Line Items]
Face amount of debt				$ 25,000,000
O&R \| Debentures \| 6.15% Debentures
Schedule of Capitalization [Line Items]
Interest rate	6.15%
Debt term	10 years
Amount of debt redeemed	$ 50,000,000
Con Edison Development \| Senior Notes \| 4.41% Senior Notes Due 2028
Schedule of Capitalization [Line Items]
Face amount of debt	$ 140,000,000
Interest rate	4.41%

Capitalization - Carrying Amounts and Fair Values of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt expense	$ 149	$ 142
Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	16,608	16,029
Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	17,369	18,147
CECONY
Debt Instrument [Line Items]
Unamortized debt discount	128	121
CECONY \| Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	13,662	13,265
CECONY \| Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	$ 14,333	$ 15,163

Short-Term Borrowing (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 1,352,000,000	$ 577,000,000
Loans outstanding under the credit agreement	0	0
Letters of credit outstanding under the credit agreement	$ 0	$ 0
Commercial Paper
Short-term Debt [Line Items]
Weighted average interest rate	2.30%	1.80%
CECONY
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 1,004,000,000	$ 150,000,000
CECONY \| Commercial Paper
Short-term Debt [Line Items]
Weighted average interest rate	2.30%	1.80%

Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 72	$ 66	$ 218	$ 197
Interest cost on projected benefit obligation	140	148	420	444
Expected return on plan assets	(258)	(243)	(775)	(726)
Recognition of net actuarial loss	172	149	516	446
Recognition of prior service cost/(credit)	(4)	(4)	(13)	(13)
TOTAL PERIODIC BENEFIT COST	122	116	366	348
Cost capitalized	(32)	(40)	(94)	(134)
Reconciliation to rate level	(22)	(14)	(68)	(28)
Total expense/(credit) recognized	68	62	204	186
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	68	61	204	184
Interest cost on projected benefit obligation	131	139	394	416
Expected return on plan assets	(245)	(229)	(734)	(689)
Recognition of net actuarial loss	163	141	488	423
Recognition of prior service cost/(credit)	(5)	(5)	(15)	(14)
TOTAL PERIODIC BENEFIT COST	112	107	337	320
Cost capitalized	(30)	(37)	(89)	(125)
Reconciliation to rate level	(24)	(16)	(74)	(32)
Total expense/(credit) recognized	$ 58	$ 54	$ 174	$ 163

Pension Benefits - Additional Information (Details) - Pension Benefits $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	$ 472
Contributions	469
CECONY
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	433
Contributions	431
CECONY \| Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 17

Other Postretirement Benefits - Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 5	$ 15	$ 15
Interest cost on accumulated other postretirement benefit obligation	11	11	32	34
Expected return on plan assets	(18)	(17)	(55)	(52)
Recognition of net actuarial loss/(gain)	2	1	6	2
Recognition of prior service cost/(credit)	(2)	(5)	(5)	(13)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(2)	(5)	(7)	(14)
Cost capitalized	(2)	2	(6)	6
Reconciliation to rate level	2	(1)	6	(3)
Total expense/(credit) recognized	(2)	(4)	(7)	(11)
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	3	10	10
Interest cost on accumulated other postretirement benefit obligation	9	9	26	28
Expected return on plan assets	(16)	(15)	(47)	(45)
Recognition of net actuarial loss/(gain)	1	0	2	(2)
Recognition of prior service cost/(credit)	(1)	(3)	(2)	(9)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST/(CREDIT)	(4)	(6)	(11)	(18)
Cost capitalized	(1)	2	(4)	7
Reconciliation to rate level	2	0	7	(1)
Total expense/(credit) recognized	$ (3)	$ (4)	$ (8)	$ (12)

Other Postretirement Benefits - Additional Information (Details) - Other Postretirement Benefits $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 6
CECONY
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 6

Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Site Contingency [Line Items]
Accrued liabilities	$ 720	$ 737
Regulatory assets	3,975	4,333
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	639	651
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	81	86
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	720	737
Regulatory assets	754	793
CECONY
Site Contingency [Line Items]
Accrued liabilities	626	637
Regulatory assets	3,595	3,925
CECONY \| Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	546	551
CECONY \| Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	80	86
CECONY \| Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	626	637
Regulatory assets	$ 653	$ 677

Environmental Matters - Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 8	$ 4	$ 17	$ 18
CECONY
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 5	$ 3	$ 14	$ 13

Environmental Matters - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Site Contingency [Line Items]
Insurance recoveries	$ 0	$ 0	$ 0	$ 0
CECONY
Site Contingency [Line Items]
Insurance recoveries	$ 0	$ 0	$ 0
CECONY \| Asbestos Proceedings
Site Contingency [Line Items]
Estimated undiscounted asbestos liability (years)			15 years
Superfund Sites \| Manufactured Gas Plant Sites \| Maximum
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)					$ 2,700
Superfund Sites \| Manufactured Gas Plant Sites \| Maximum \| CECONY
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)					$ 2,500

Environmental Matters - Accrued Liability (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Site Contingency [Line Items]
Regulatory assets	$ 3,975	$ 4,333
Asbestos Suits
Site Contingency [Line Items]
Accrued liability	8	8
Regulatory assets	8	8
Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	80	84
Regulatory assets	6	10
CECONY
Site Contingency [Line Items]
Regulatory assets	3,595	3,925
CECONY \| Asbestos Suits
Site Contingency [Line Items]
Accrued liability	7	7
Regulatory assets	7	7
CECONY \| Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	76	80
Regulatory assets	$ 6	$ 10

Other Material Contingencies - Manhattan Explosion and Fire (Details) $ in Millions		1 Months Ended
	Mar. 12, 2014 building people	Feb. 28, 2017 USD ($)	Sep. 30, 2018 USD ($) lawsuit	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Accrued regulatory liability			$ 4,624	$ 4,577
Settlement of Gas Proceedings
Loss Contingencies [Line Items]
Accrued regulatory liability			$ 16	$ 27
Manhattan Explosion and Fire
Loss Contingencies [Line Items]
Number of buildings destroyed by fire \| building	2
Number of people died in explosion and fire incident \| people	8
Number of people injured in explosion and fire incident (more than) \| people	50
Amount of costs that will not recover from customers		$ 126
Number of pending lawsuits \| lawsuit			80
Manhattan Explosion and Fire \| Settlement of Gas Proceedings
Loss Contingencies [Line Items]
Accrued regulatory liability		$ 27

Other Material Contingencies - Manhattan Steam Main Rupture (Details) $ in Millions	Sep. 30, 2018 USD ($)
Property Damage, Clean Up and Other Response Costs Related with Manhattan Steam Main Rupture
Loss Contingencies [Line Items]
Loss contingency	$ 10
Capital, Retirement and Other Costs Related with Manhattan Steam Main Rupture
Loss Contingencies [Line Items]
Loss contingency	$ 7

Other Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	1 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 1,991	$ 2,073
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,148
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	659
Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	114
Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	70
0 – 3 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,341
0 – 3 years \| Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	744
0 – 3 years \| Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	434
0 – 3 years \| Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	93
0 – 3 years \| Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	70
4 – 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	428
4 – 10 years \| Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	404
4 – 10 years \| Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	24
4 – 10 years \| Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
4 – 10 years \| Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	222
Greater than 10 years \| Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years \| Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	201
Greater than 10 years \| Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	21
Greater than 10 years \| Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Sempra Solar Holdings, LLC
Guarantor Obligations [Line Items]
Purchase price	$ 1,540

Other Material Contingencies - Con Edison Transmission (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2014
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 1,991	$ 2,073
Payment Guarantee by CET Electric of Contributions to New York Transco LLC
Guarantor Obligations [Line Items]
Ownership interest, percentage			45.70%
Estimated project cost percentage	175.00%
Financial Guarantee in Behalf of CET Gas for Proposed Gas Transmission Project
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 125

Other Material Contingencies - Other (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 1,991	$ 2,073
Financial Guarantee for Indemnity Agreements for Surety Bonds
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 70

Income Tax - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
Income Tax - Additional Information (Details) - USD ($)	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Taxes Disclosure [Line Items]
Income tax expense		$ 175,000,000	$ 270,000,000	$ 330,000,000	$ 599,000,000
TCJA, re-measurement of deferred tax assets						$ 42,000,000
Decrease in net deferred tax liabilities						16,000,000
Accrued regulatory liability for future income tax						58,000,000
Estimated liability for uncertain tax positions		11,000,000		11,000,000
Effective income tax rate reconciliation, uncertainty of taxes				10,000,000
Effective income tax rate reconciliation, uncertainty net of federal taxes				9,000,000
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate		11,000,000		11,000,000
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate, net of federal taxes		10,000,000		10,000,000
Interest expense for uncertain tax positions		0	0	0	0
Penalties for uncertain tax positions		0	0	0	0
Accrued interest on uncertain tax positions		0		0		0
Federal
Income Taxes Disclosure [Line Items]
NOL carryover						563,000,000
Settlement of uncertain federal tax positions	$ 3,000,000
Federal \| Utilities
Income Taxes Disclosure [Line Items]
Additional depreciation						477,000,000
CECONY
Income Taxes Disclosure [Line Items]
Income tax expense		125,000,000	$ 242,000,000	274,000,000	$ 551,000,000
Decrease in net deferred tax liabilities						51,000,000
Accrued regulatory liability for future income tax						51,000,000
Estimated liability for uncertain tax positions		$ 5,000,000		5,000,000
Effective income tax rate reconciliation, uncertainty of taxes				$ 3,000,000
CECONY \| Federal
Income Taxes Disclosure [Line Items]
NOL carryover						$ 153,000,000

Income Tax - Income Tax Reconciliation (Details)	3 Months Ended		9 Months Ended
Income Tax - Income Tax Reconciliation (Details)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
STATUTORY TAX RATE
Federal	21.00%	35.00%	21.00%	35.00%
Changes in computed taxes resulting from:
State income tax	5.00%	5.00%	5.00%	4.00%
Cost of removal			1.00%	1.00%
Other plant-related items	(1.00%)	(1.00%)	(1.00%)	(1.00%)
Renewable energy credits	(1.00%)	(1.00%)	(1.00%)	(1.00%)
TCJA deferred tax re-measurement	7.00%	0.00%	3.00%	0.00%
Amortization of excess deferred federal income taxes	(2.00%)	(0.00%)	(3.00%)	(0.00%)
Other	(1.00%)	(1.00%)	(1.00%)	(1.00%)
Effective tax rate	28.00%	37.00%	24.00%	37.00%
CECONY
STATUTORY TAX RATE
Federal	21.00%	35.00%	21.00%	35.00%
Changes in computed taxes resulting from:
State income tax	5.00%	4.00%	5.00%	4.00%
Cost of removal			1.00%	1.00%
Other plant-related items	(1.00%)	(1.00%)	(1.00%)	(1.00%)
Renewable energy credits	(0.00%)	(0.00%)	(0.00%)	(0.00%)
TCJA deferred tax re-measurement	0.00%	0.00%	0.00%	0.00%
Amortization of excess deferred federal income taxes	(2.00%)	(0.00%)	(3.00%)	(0.00%)
Other	(1.00%)	0.00%	(1.00%)	(1.00%)
Effective tax rate	22.00%	38.00%	22.00%	38.00%

Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 3,328	$ 3,211	$ 9,388	$ 9,072
Depreciation and amortization	360	337	1,061	998
Operating income/(loss)	826	914	2,007	2,189
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	18	19	55	54
Operating income/(loss)	25	29	59	63
Con Edison Transmission
Segment Reporting Information [Line Items]
Depreciation and amortization			1	0
Operating income/(loss)	(2)	(2)	(5)	(6)
CECONY
Segment Reporting Information [Line Items]
Total revenues	2,899	2,799	8,121	7,948
Depreciation and amortization	322	300	949	891
Operating income/(loss)	764	836	1,850	1,999
CECONY \| Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	248	232	732	690
Operating income/(loss)	850	883	1,421	1,561
CECONY \| Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	52	47	152	137
Operating income/(loss)	(34)	(6)	369	379
CECONY \| Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	22	21	65	64
Operating income/(loss)	(52)	(41)	60	59
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	19	18	57	53
Operating income/(loss)	42	50	110	131
O&R \| Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	14	13	41	38
Operating income/(loss)	52	60	79	94
O&R \| Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	5	5	16	15
Operating income/(loss)	(10)	(10)	31	37
Operating segment
Segment Reporting Information [Line Items]
Total revenues	3,328	3,211	9,388	9,072
Operating segment \| Clean Energy Businesses
Segment Reporting Information [Line Items]
Total revenues	181	177	573	460
Operating segment \| Con Edison Transmission
Segment Reporting Information [Line Items]
Total revenues	1	1	3	1
Operating segment \| CECONY
Segment Reporting Information [Line Items]
Total revenues	2,899	2,799	8,121	7,948
Operating segment \| CECONY \| Electric
Segment Reporting Information [Line Items]
Total revenues	2,571	2,469	6,107	6,079
Operating segment \| CECONY \| Gas
Segment Reporting Information [Line Items]
Total revenues	264	268	1,540	1,421
Operating segment \| CECONY \| Steam
Segment Reporting Information [Line Items]
Total revenues	64	62	474	448
Operating segment \| O&R
Segment Reporting Information [Line Items]
Total revenues	246	234	691	667
Operating segment \| O&R \| Electric
Segment Reporting Information [Line Items]
Total revenues	212	206	505	495
Operating segment \| O&R \| Gas
Segment Reporting Information [Line Items]
Total revenues	34	28	186	172
Other
Segment Reporting Information [Line Items]
Total revenues	1	0	0	(4)
Depreciation and amortization	1	0	(1)	0
Operating income/(loss)	(3)	1	(7)	2
Inter-segment \| CECONY
Segment Reporting Information [Line Items]
Total revenues	(25)	(25)	(74)	(72)
Inter-segment \| CECONY \| Electric
Segment Reporting Information [Line Items]
Total revenues	4	4	12	12
Inter-segment \| CECONY \| Gas
Segment Reporting Information [Line Items]
Total revenues	2	2	6	5
Inter-segment \| CECONY \| Steam
Segment Reporting Information [Line Items]
Total revenues	$ 19	$ 19	$ 56	$ 55

Derivative Instruments and Hedging Activities - Fair Values of Commodity Derivatives Including Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	$ (1)	$ (17)
Gross Amounts Offset	0	0
Net Amounts of Assets/ (Liabilities)	(1)	(17)
Margin deposits	7	12
CECONY
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	9	(14)
Gross Amounts Offset	(1)	(1)
Net Amounts of Assets/ (Liabilities)	8	(15)
Margin deposits	6	11
Fair Value of Derivative Liabilities, Current
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(41)	(67)
Gross Amounts Offset	23	50
Net Amounts of Assets/ (Liabilities)	(18)	(17)
Fair Value of Derivative Liabilities, Current \| CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(19)	(26)
Gross Amounts Offset	15	14
Net Amounts of Assets/ (Liabilities)	(4)	(12)
Fair Value of Derivative Liabilities, Noncurrent
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(26)	(43)
Gross Amounts Offset	13	5
Net Amounts of Assets/ (Liabilities)	(13)	(38)
Fair Value of Derivative Liabilities, Noncurrent \| CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(20)	(36)
Gross Amounts Offset	11	4
Net Amounts of Assets/ (Liabilities)	(9)	(32)
Fair Value of Derivative Liabilities
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(67)	(110)
Gross Amounts Offset	36	55
Net Amounts of Assets/ (Liabilities)	(31)	(55)
Fair Value of Derivative Liabilities \| CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(39)	(62)
Gross Amounts Offset	26	18
Net Amounts of Assets/ (Liabilities)	(13)	(44)
Fair Value of Derivative Assets, Current
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	45	83
Gross Amounts Offset	(23)	(51)
Net Amounts of Assets/ (Liabilities)	22	32
Fair Value of Derivative Assets, Current \| CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	32	39
Gross Amounts Offset	(16)	(15)
Net Amounts of Assets/ (Liabilities)	16	24
Fair Value of Derivative Assets, Noncurrent
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	21	10
Gross Amounts Offset	(13)	(4)
Net Amounts of Assets/ (Liabilities)	8	6
Fair Value of Derivative Assets, Noncurrent \| CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	16	9
Gross Amounts Offset	(11)	(4)
Net Amounts of Assets/ (Liabilities)	5	5
Fair Value of Derivative Assets
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	66	93
Gross Amounts Offset	(36)	(55)
Net Amounts of Assets/ (Liabilities)	30	38
Fair Value of Derivative Assets \| CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	48	48
Gross Amounts Offset	(27)	(19)
Net Amounts of Assets/ (Liabilities)	$ 21	$ 29

Derivative Instruments and Hedging Activities - Realized and Unrealized Gains (Losses) on Commodity Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ 6	$ (3)	$ (6)	$ (28)
Total deferred gains/(losses)	36	(63)	31	(155)
Net deferred gains/(losses)	42	(66)	25	(183)
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(7)	(42)	(8)	(150)
Purchased power expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	(47)	(1)	(161)
Non-utility revenue
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(7)	5	(7)	11
Non-utility operating revenue
Pre-tax gains/(losses) recognized in income
Unrealized gain/(loss) on derivatives	(4)	6	(6)	2
Deferred Derivative Gains, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	6	(4)	(11)	(26)
Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	0	1	5	(2)
Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	25	(11)	21	10
Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(4)	(40)	(13)	(125)
Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	15	(12)	23	(40)
CECONY
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	8	(2)	(6)	(24)
Total deferred gains/(losses)	33	(55)	30	(141)
Net deferred gains/(losses)	41	(57)	24	(165)
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY \| Purchased power expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY \| Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY \| Non-utility revenue
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY \| Deferred Derivative Gains, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	6	(3)	(10)	(22)
CECONY \| Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	2	1	4	(2)
CECONY \| Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	25	(9)	23	11
CECONY \| Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(6)	(38)	(14)	(116)
CECONY \| Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ 14	$ (8)	$ 21	$ (36)

Derivative Instruments and Hedging Activities - Hedged Volume of Derivative Transactions (Details) gal in Thousands	Sep. 30, 2018 gal MMBTU MW MWh
Electric Energy
Derivatives, Fair Value [Line Items]
Notional amount \| MWh	30,590,984
Capacity
Derivatives, Fair Value [Line Items]
Notional amount \| MW	8,134
Natural Gas
Derivatives, Fair Value [Line Items]
Notional amount \| MMBTU	195,821,882
Refined Fuels
Derivatives, Fair Value [Line Items]
Notional amount \| gal	2,688
CECONY \| Electric Energy
Derivatives, Fair Value [Line Items]
Notional amount \| MWh	27,983,800
CECONY \| Capacity
Derivatives, Fair Value [Line Items]
Notional amount \| MW	3,300
CECONY \| Natural Gas
Derivatives, Fair Value [Line Items]
Notional amount \| MMBTU	182,820,000
CECONY \| Refined Fuels
Derivatives, Fair Value [Line Items]
Notional amount \| gal	2,688

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Energy supply and hedging activities credit exposure total	$ 107
Makeup of net credit exposure independent system operators	44
Makeup of net credit exposure with investment-grade counterparties	25
Makeup of net credit exposure non-investment grade/non-rated counterparties	22
Makeup of net credit exposure with commodity exchange brokers	16
CECONY
Investment Holdings [Line Items]
Energy supply and hedging activities credit exposure total	17
Makeup of net credit exposure with investment-grade counterparties	10
Makeup of net credit exposure with commodity exchange brokers	7
Clean Energy Businesses \| Coram \| Interest Rate Swap
Investment Holdings [Line Items]
Derivative, fixed interest rate			2.0855%
Derivative asset	$ 1	$ 0

Derivative Instruments and Hedging Activities - Credit-Risk-Related Contingent Features (Details) $ in Millions	Sep. 30, 2018 USD ($)
Derivatives, Fair Value [Line Items]
Aggregate fair value – net liabilities	$ 19
Collateral posted	13
Downgrade One Level from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	0
Downgrade to Below Investment Grade from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	17
Derivatives in net asset position additional collateral	22
Additional Collateral Required Due to Loss of Unsecured Credit
Derivatives, Fair Value [Line Items]
Collateral posted	1
CECONY
Derivatives, Fair Value [Line Items]
Aggregate fair value – net liabilities	9
Collateral posted	10
CECONY \| Downgrade One Level from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	0
CECONY \| Downgrade to Below Investment Grade from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	$ 7

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer out of level 3	$ 1	$ 0
CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer out of level 3	1	$ 0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(10)
Level 3 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer out of level 3	1
Derivative liabilities transferred from Level 3 to Level 2			$ 11
Commodity \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer out of level 3	1
Derivative liabilities transferred from Level 3 to Level 2			10
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	471		453
Recurring \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	433		414
Recurring \| Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(14)		(39)
Recurring \| Netting Adjustment \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(10)		(7)
Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	317		288
Recurring \| Level 1 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	296		263
Recurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	160		197
Recurring \| Level 2 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	146		154
Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	8		7
Recurring \| Level 3 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1		4
Recurring \| Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	37		50
Derivative liabilities	31		55
Recurring \| Commodity \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	27		40
Derivative liabilities	13		44
Recurring \| Commodity \| Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(14)		(39)
Derivative liabilities	(22)		(52)
Recurring \| Commodity \| Netting Adjustment \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	(10)		(7)
Derivative liabilities	(14)		(18)
Recurring \| Commodity \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3		5
Derivative liabilities	5		8
Recurring \| Commodity \| Level 1 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3		3
Derivative liabilities	4		5
Recurring \| Commodity \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	40		77
Derivative liabilities	30		93
Recurring \| Commodity \| Level 2 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33		40
Derivative liabilities	22		57
Recurring \| Commodity \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	8		7
Derivative liabilities	18		6
Recurring \| Commodity \| Level 3 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1		4
Derivative liabilities	1		0
Recurring \| Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1		0
Recurring \| Interest rate swap \| Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Interest rate swap \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Interest rate swap \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1		0
Recurring \| Interest rate swap \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	433		403
Recurring \| Other \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	406		374
Recurring \| Other \| Netting Adjustment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Other \| Netting Adjustment \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Other \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	314		283
Recurring \| Other \| Level 1 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	293		260
Recurring \| Other \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	119		120
Recurring \| Other \| Level 2 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	113		114
Recurring \| Other \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0
Recurring \| Other \| Level 3 \| CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 0		$ 0

Fair Value Measurements - Schedule of Commodity Derivatives (Details) - Level 3 $ in Millions	Sep. 30, 2018 USD ($) $ / kW-month $ / MWh $ / Dt
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (10)
CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	0
Electricity \| Forward energy prices
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (7)
Electricity \| Forward energy prices \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	18.33
Electricity \| Forward energy prices \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	79.20
Electricity \| Forward capacity prices
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives
Electricity \| Forward capacity prices \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / kW-month	1.70
Electricity \| Forward capacity prices \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / kW-month	8.84
Electricity \| Forward capacity prices \| CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (1)
Electricity \| Forward capacity prices \| CECONY \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / kW-month	1.70
Electricity \| Forward capacity prices \| CECONY \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / kW-month	7.20
Natural Gas \| Forward natural gas prices
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (4)
Natural Gas \| Forward natural gas prices \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / Dt	0.96
Natural Gas \| Forward natural gas prices \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / Dt	10.51
Transmission Congestion Contracts/Financial Transmission Rights \| Inter-zonal forward price curves adjusted for historical zonal losses
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ 1
Transmission Congestion Contracts/Financial Transmission Rights \| Inter-zonal forward price curves adjusted for historical zonal losses \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	0.37
Transmission Congestion Contracts/Financial Transmission Rights \| Inter-zonal forward price curves adjusted for historical zonal losses \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	5.45
Transmission Congestion Contracts \| Inter-zonal forward price curves adjusted for historical zonal losses \| CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ 1
Transmission Congestion Contracts \| Inter-zonal forward price curves adjusted for historical zonal losses \| CECONY \| Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	0.45
Transmission Congestion Contracts \| Inter-zonal forward price curves adjusted for historical zonal losses \| CECONY \| Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) \| $ / MWh	4.18

Fair Value Measurements - Reconciliation of Assets and Liabilities Measured at Level 3 Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ (4)	$ (10)	$ 1	$ 1
Included in earnings	4	7	4	8
Included in regulatory assets and liabilities	(4)	(13)	(7)	(21)
Purchases			0	1
Settlements	(6)	(4)	(9)	(9)
Transfer out of level 3			1	0
Ending balance	(10)	(20)	(10)	(20)
CECONY
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	(6)	4	1
Included in earnings	2	1	4	1
Included in regulatory assets and liabilities	0	(8)	(5)	(14)
Purchases			0	1
Settlements	(2)	(1)	(4)	(3)
Transfer out of level 3			1	0
Ending balance	$ 0	$ (14)	$ 0	$ (14)

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Non-utility revenue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value relating to Level 3 commodity derivative assets and liabilities	$ (1)		$ (5)
Purchased power cost
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value relating to Level 3 commodity derivative assets and liabilities		$ 4		$ 2
Clean Energy Businesses \| Non-utility revenue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on Level 3 commodity derivative assets and liabilities	(1)	0	(4)	0
Change in fair value relating to Level 3 commodity derivative assets and liabilities		0		0
Clean Energy Businesses \| Purchased power cost
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on Level 3 commodity derivative assets and liabilities	0	$ 4	0	$ 3
Change in fair value relating to Level 3 commodity derivative assets and liabilities	$ 0		$ 0

Variable Interest Entities (Details) $ in Millions	9 Months Ended
Variable Interest Entities (Details) $ in Millions	Sep. 30, 2018 USD ($) MW
Sempra Solar Holdings, LLC
Variable Interest Entity [Line Items]
Ownership percentage	50.00%
Variable Interest Entity, Not Primary Beneficiary \| Copper Mountain Solar 3 (d) \| Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	128
Power Purchase Agreement Term (in Years)	20 years
Maximum Exposure to Loss	$ 169
Variable Interest Entity, Not Primary Beneficiary \| Mesquite Solar 1 (d) \| Arizona
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	83
Power Purchase Agreement Term (in Years)	20 years
Maximum Exposure to Loss	$ 101
Variable Interest Entity, Not Primary Beneficiary \| Copper Mountain Solar 2 (d) \| Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	75
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 80
Variable Interest Entity, Not Primary Beneficiary \| California Solar (d) \| California
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	55
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 59
Variable Interest Entity, Not Primary Beneficiary \| Broken Bow II (d) \| Nebraska
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	38
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 42
Variable Interest Entity, Primary Beneficiary \| Texas Solar 4
Variable Interest Entity [Line Items]
Percentage of variable interests	80.00%
Maximum exposure for consolidated investments	$ 7
Variable Interest Entity, Primary Beneficiary \| Texas Solar 4 \| Texas
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) \| MW	32
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 19
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure
Variable Interest Entity [Line Items]
Percentage of variable interests	50.00%

Acquisitions (Details) $ in Millions	1 Months Ended
Acquisitions (Details) $ in Millions	Sep. 30, 2018 USD ($) MW
Sempra Solar Holdings, LLC
Business Acquisition [Line Items]
Ownership percentage	50.00%
Sempra Solar Holdings, LLC \| Renewable Electric Production Projects
Business Acquisition [Line Items]
Project generating capacity (in mw) \| MW	379
Con Edison Development \| Renewable Electric Production Projects
Business Acquisition [Line Items]
Project debt	$ 506
Sempra Solar Holdings, LLC \| Renewable Electric Production Projects
Business Acquisition [Line Items]
Project generating capacity (in mw) \| MW	981
Project debt	$ 576
Sempra Solar Holdings, LLC
Business Acquisition [Line Items]
Purchase price	1,540
Sempra Solar Holdings, LLC \| Con Edison Development
Business Acquisition [Line Items]
Purchase price	$ 1,540

Short-Term Borrowing	9 Months Ended
Short-Term Borrowing	Sep. 30, 2018
Debt Disclosure [Abstract]
Short-Term Borrowing	Short-Term Borrowing At September 30, 2018, Con Edison had $1,352 million of commercial paper outstanding of which $1,004 million was outstanding under CECONY’s program. The weighted average interest rate at September 30, 2018 was 2.3 percent for both Con Edison and CECONY. At December 31, 2017, Con Edison had $577 million of commercial paper outstanding of which $150 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2017 was 1.8 percent for both Con Edison and CECONY. At September 30, 2018 and December 31, 2017, no loans were outstanding under the credit agreement (Credit Agreement). An immaterial amount of letters of credit were outstanding under the Credit Agreement as of September 30, 2018 and December 31, 2017.