Consolidated Statement Of Capitalization (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Pension plan liability adjustments, tax	$ (34)	$ (22)
Unrealized gains/(losses) on derivatives qualified as cash flow hedges, tax and reclassification adjustment	(2)	(2)
Preferred stock, shares authorized	1,915,319	1,915,319
Preferred stock, no par value
Preferred stock, stated per share amount	$ 5	$ 5
CECONY [Member]
Pension plan liability adjustments, tax	(3)	(2)
Unrealized gains/(losses) on derivatives qualified as cash flow hedges, tax and reclassification adjustment	$ (2)	$ (2)
Preferred stock, shares authorized	1,915,319	1,915,319
Preferred stock, no par value
Preferred stock, stated per share amount	$ 5	$ 5
Cumulative Preferred Stock [Member]
Preferred stock, shares authorized	6,000,000	6,000,000
Preferred stock, par value	$ 100	$ 100
Cumulative Preferred Stock [Member] | CECONY [Member]
Preferred stock, shares authorized	6,000,000	6,000,000
Preferred stock, par value	$ 100	$ 100