Consolidated Statement of Shareholder's Equity (USD $) In Millions, except Share data	Total	CECONY [Member]	Common Stock [Member]	Common Stock [Member] CECONY [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] CECONY [Member]	Retained Earnings [Member]	Retained Earnings [Member] CECONY [Member]	Treasury Stock [Member]	Capital Stock Expense [Member]	Capital Stock Expense [Member] CECONY [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] CECONY [Member]	Noncontrolling Interest [Member]	Repurchased Con Edison Stock [Member] CECONY [Member]
BALANCE at Dec. 31, 2013		$ 10,847		$ 589		$ 4,234		$ 7,053			$ (61)		$ (6)		$ (962)
BALANCE at Dec. 31, 2013	12,245		32		4,995		8,338		(1,034)	(61)		(25)
BALANCE (in shares) at Dec. 31, 2013			292,872,396	235,488,094					23,210,200
Net income for common stock	361	334					361
NET INCOME	361	334						334
Common stock dividends	(184)	(178)					(184)	(178)
Issuance of common shares for stock plans, net of repurchases					(2)				2
Issuance of common shares for stock plans, net of repurchases (in shares)			51,656						(51,656)
Other comprehensive income	4	1										4	1
BALANCE at Mar. 31, 2014	12,426		32		4,993		8,515		(1,032)	(61)		(21)
BALANCE at Mar. 31, 2014		11,004		589		4,234		7,209			(61)		(5)		(962)
BALANCE (in shares) at Mar. 31, 2014			292,924,052	235,488,094					23,158,544
BALANCE at Dec. 31, 2014	12,576	11,188		589		4,234		7,399			(61)		(11)		(962)
BALANCE at Dec. 31, 2014	12,585		32		4,991		8,691		(1,032)	(61)		(45)		9
BALANCE (in shares) at Dec. 31, 2014			292,876,196	235,488,094					23,206,400
Net income for common stock	370	348					370
NET INCOME	370	348						348
Common stock dividends	(190)	(338)					(190)	(338)
Issuance of common shares for stock plans, net of repurchases					2				(2)
Issuance of common shares for stock plans, net of repurchases (in shares)			24,600						(24,600)
Other comprehensive income	5											5
Noncontrolling interest	9
BALANCE at Mar. 31, 2015	12,770		32		4,993		8,871		(1,034)	(61)		(40)		9
BALANCE at Mar. 31, 2015	$ 12,761	$ 11,198		$ 589		$ 4,234		$ 7,409			$ (61)		$ (11)		$ (962)
BALANCE (in shares) at Mar. 31, 2015			292,900,796	235,488,094					23,181,800