Consolidated Statement of Capitalization (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
TOTAL COMMON SHAREHOLDERS' EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS	$ 11,922	$ 11,494
TOTAL COMMON SHAREHOLDERS' EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS (in shares)	292,871,896	292,888,521
Pension plan liability adjustments, net	(50)	(55)
Unrealized gains/(losses) on derivatives qualified as cash flow hedges, less reclassification adjustment for gains/(losses) included in net income and reclassification adjustment	(3)	(3)
TOTAL ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAXES	(53)	(58)
TOTAL COMMON SHAREHOLDERS' EQUITY (SEE STATEMENT OF COMMON SHAREHOLDER'S EQUITY)	11,869	11,436
Preferred stock		213
CECONY [Member]
TOTAL COMMON SHAREHOLDERS' EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS	10,561	10,226
TOTAL COMMON SHAREHOLDERS' EQUITY BEFORE ACCUMULATED OTHER COMPREHENSIVE LOSS (in shares)	235,488,094	235,488,094
Pension plan liability adjustments, net	(6)	(5)
Unrealized gains/(losses) on derivatives qualified as cash flow hedges, less reclassification adjustment for gains/(losses) included in net income and reclassification adjustment	(3)	(3)
TOTAL ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAXES	(9)	(8)
TOTAL COMMON SHAREHOLDERS' EQUITY (SEE STATEMENT OF COMMON SHAREHOLDER'S EQUITY)	10,552	10,218
Preferred stock		213
Cumulative Preferred Stock [Member]
Preferred stock		175
Preferred stock (in shares)		1,915,319
Cumulative Preferred Stock [Member] | CECONY [Member]
Preferred stock		175
Preferred stock (in shares)		1,915,319
4.65% Series C [Member] | Cumulative Preferred Stock [Member]
Preferred stock		16
Preferred stock (in shares)		153,296
4.65% Series C [Member] | Cumulative Preferred Stock [Member] | CECONY [Member]
Preferred stock		16
Preferred stock (in shares)		153,296
4.65% Series D [Member] | Cumulative Preferred Stock [Member]
Preferred stock		22
Preferred stock (in shares)		222,330
4.65% Series D [Member] | Cumulative Preferred Stock [Member] | CECONY [Member]
Preferred stock		$ 22
Preferred stock (in shares)		222,330