Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
CURRENT ASSETS
Cash and temporary cash investments	$ 394	$ 648
Accounts receivable - customers, less allowance for uncollectible accounts	1,222	1,123
Other receivables, less allowance for uncollectible accounts	228	303
Accrued unbilled revenue	516	474
Fuel oil, gas in storage, materials and supplies, at average cost	330	356
Prepayments	159	145
Regulatory assets	74	164
Deferred tax assets - current	296	266
Other current assets	232	159
TOTAL CURRENT ASSETS	3,451	3,638
INVESTMENTS	467	455
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	555	89
Construction work in progress	83	39
NET PLANT	26,939	25,093
UTILITY PLANT, AT ORIGINAL COST
General	2,302	1,944
TOTAL	31,847	29,775
Less: Accumulated depreciation	6,573	6,051
Net	25,274	23,724
Construction work in progress	1,027	1,241
NET UTILITY PLANT	26,301	24,965
OTHER NONCURRENT ASSETS
Goodwill	429	429
Intangible assets, less accumulated amortization of $4 and $3 in 2012 and 2011, respectively	2	3
Regulatory assets	9,705	9,431
Other deferred charges and noncurrent assets	216	165
TOTAL OTHER NONCURRENT ASSETS	10,352	10,028
TOTAL ASSETS	41,209	39,214
CURRENT LIABILITIES
Long-term debt due within one year	706	530
Notes payable	539
Accounts payable	1,215	955
Customer deposits	304	303
Accrued taxes	162	188
Accrued interest	153	160
Accrued wages	94	91
Fair value of derivative liabilities	47	169
Regulatory liabilities	183	118
Other current liabilities	542	473
TOTAL CURRENT LIABILITIES	3,945	2,987
NONCURRENT LIABILITIES
Obligations under capital leases	2	2
Provision for injuries and damages	149	181
Pensions and retiree benefits	4,678	4,835
Superfund and other environmental costs	545	489
Asset retirement obligations	159	145
Fair value of derivative liabilities	31	48
Other noncurrent liabilities	125	131
TOTAL NONCURRENT LIABILITIES	5,689	5,831
DEFERRED CREDITS AND REGULATORY LIABILITIES
Deferred income taxes and investment tax credits	8,372	7,563
Regulatory liabilities	1,202	977
Other deferred credits	70	64
TOTAL DEFERRED CREDITS AND REGULATORY LIABILITIES	9,644	8,604
LONG-TERM DEBT (See Statement of Capitalization)	10,062	10,143
SHAREHOLDERS' EQUITY
Common shareholders' equity (See Statement of Common Shareholder's Equity)	11,869	11,436
Preferred stock		213
TOTAL SHAREHOLDERS' EQUITY	11,869	11,649
Total Liabilities and Shareholders' Equity	41,209	39,214
Electric Transmission [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	22,376	21,114
Gas Transmission [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	5,120	4,734
Steam Plant [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	2,049	1,983
CECONY [Member]
CURRENT ASSETS
Cash and temporary cash investments	353	372
Accounts receivable - customers, less allowance for uncollectible accounts	1,108	977
Other receivables, less allowance for uncollectible accounts	106	102
Accrued unbilled revenue	406	366
Accounts receivable from affiliated companies	61	54
Fuel oil, gas in storage, materials and supplies, at average cost	285	308
Prepayments	81	85
Regulatory assets	60	140
Deferred tax assets - current	193	157
Other current assets	134	100
TOTAL CURRENT ASSETS	2,787	2,661
INVESTMENTS	207	177
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	6	6
NET PLANT	24,745	23,502
UTILITY PLANT, AT ORIGINAL COST
General	2,126	1,785
TOTAL	29,801	27,854
Less: Accumulated depreciation	6,009	5,523
Net	23,792	22,331
Construction work in progress	947	1,165
NET UTILITY PLANT	24,739	23,496
OTHER NONCURRENT ASSETS
Goodwill	245
Regulatory assets	8,972	8,750
Other deferred charges and noncurrent assets	174	128
TOTAL OTHER NONCURRENT ASSETS	9,146	8,878
TOTAL ASSETS	36,885	35,218
CURRENT LIABILITIES
Long-term debt due within one year	700	525
Notes payable	421
Accounts payable	989	774
Accounts payable to affiliated companies	22	16
Customer deposits	292	290
Accrued taxes	37	32
Accrued taxes to affiliated companies	215	126
Accrued interest	133	133
Accrued wages	84	81
Fair value of derivative liabilities	28	98
Regulatory liabilities	145	79
Other current liabilities	446	396
TOTAL CURRENT LIABILITIES	3,512	2,550
NONCURRENT LIABILITIES
Obligations under capital leases	2	2
Provision for injuries and damages	141	173
Pensions and retiree benefits	4,220	4,337
Superfund and other environmental costs	433	373
Asset retirement obligations	158	145
Fair value of derivative liabilities	11	24
Other noncurrent liabilities	115	120
TOTAL NONCURRENT LIABILITIES	5,080	5,174
DEFERRED CREDITS AND REGULATORY LIABILITIES
Deferred income taxes and investment tax credits	7,452	6,921
Regulatory liabilities	1,077	861
Other deferred credits	67	61
TOTAL DEFERRED CREDITS AND REGULATORY LIABILITIES	8,596	7,843
LONG-TERM DEBT (See Statement of Capitalization)	9,145	9,220
SHAREHOLDERS' EQUITY
Common shareholders' equity (See Statement of Common Shareholder's Equity)	10,552	10,218
Preferred stock		213
TOTAL SHAREHOLDERS' EQUITY	10,552	10,431
Total Liabilities and Shareholders' Equity	36,885	35,218
CECONY [Member] | Electric Transmission [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	21,079	19,886
CECONY [Member] | Gas Transmission [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	4,547	4,200
CECONY [Member] | Steam Plant [Member]
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	$ 2,049	$ 1,983