Consolidated Statement of Common Shareholders' 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]	Repurchased Con Edison Stock [Member] CECONY [Member]	Noncontrolling Interest [Member]
BALANCE at Dec. 31, 2012		$ 10,552		$ 589		$ 4,234		$ 6,761			$ (61)		$ (9)	$ (962)
BALANCE at Dec. 31, 2012	11,869		32		4,991		7,997		(1,037)	(61)		(53)
BALANCE (in shares) at Dec. 31, 2012			292,871,896	235,488,094					23,210,700
Net income for common stock	192						192
NET INCOME		277						277
Common stock dividends	(180)	(182)					(180)	(182)
Issuance of common shares for stock plans, net of repurchases	5				(2)				7
Issuance of common shares for stock plans, net of repurchases (in shares)			95,468
Issuance of common shares for stock plans, net of repurchases (in shares)									(95,468)
Other comprehensive income	3	0										3	0
BALANCE at Mar. 31, 2013	11,889		32		4,989		8,009		(1,030)	(61)		(50)
BALANCE at Mar. 31, 2013		10,647		589		4,234		6,856			(61)		(9)	(962)
BALANCE (in shares) at Mar. 31, 2013			292,967,364	235,488,094					23,115,232
BALANCE at Dec. 31, 2012		10,552		589		4,234					(61)			(962)
BALANCE at Dec. 31, 2012	11,869									(61)
BALANCE (in shares) at Dec. 31, 2012				235,488,094
Net income for common stock	828	831
NET INCOME	828	831
BALANCE at Sep. 30, 2013	12,166				4,990					(61)
BALANCE at Sep. 30, 2013		10,838		589		4,234					(61)		(9)	(962)
BALANCE (in shares) at Sep. 30, 2013				235,488,094
BALANCE at Mar. 31, 2013		10,647		589		4,234		6,856			(61)		(9)	(962)
BALANCE at Mar. 31, 2013	11,889		32		4,989		8,009		(1,030)	(61)		(50)
BALANCE (in shares) at Mar. 31, 2013			292,967,364	235,488,094					23,115,232
Net income for common stock	172						172
NET INCOME		153						153
Common stock dividends	(180)	(182)					(180)	(182)
Issuance of common shares for stock plans, net of repurchases					1				(1)
Issuance of common shares for stock plans, net of repurchases (in shares)			(4,078)
Issuance of common shares for stock plans, net of repurchases (in shares)									4,078
Other comprehensive income	2	0										2	0
BALANCE at Jun. 30, 2013	11,883		32		4,990		8,001		(1,031)	(61)		(48)
BALANCE at Jun. 30, 2013		10,618		589		4,234		6,827			(61)		(9)	(962)
BALANCE (in shares) at Jun. 30, 2013			292,963,286	235,488,094					23,119,310
Net income for common stock	464	401					464
NET INCOME	464	401						401
Common stock dividends	(180)	(181)					(180)	(181)
Issuance of common shares for stock plans, net of repurchases	(3)								(3)
Issuance of common shares for stock plans, net of repurchases (in shares)			(34,931)
Issuance of common shares for stock plans, net of repurchases (in shares)									34,931
Other comprehensive income	2											2
BALANCE at Sep. 30, 2013	12,166		32		4,990		8,285		(1,034)	(61)		(46)
BALANCE at Sep. 30, 2013		10,838		589		4,234		7,047			(61)		(9)	(962)
BALANCE (in shares) at Sep. 30, 2013			292,928,355	235,488,094					23,154,241
BALANCE at Dec. 31, 2013	12,245	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						361
NET INCOME		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
Issuance of common shares for stock plans, net of repurchases (in shares)									(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, 2013	12,245	10,847		589		4,234					(61)			(962)
BALANCE at Dec. 31, 2013	12,245									(61)
BALANCE (in shares) at Dec. 31, 2013				235,488,094
Net income for common stock	1,010	905
NET INCOME	1,010	905
Noncontrolling interest	9														9
BALANCE at Sep. 30, 2014	12,716				4,993					(61)					9
BALANCE at Sep. 30, 2014	12,707	11,219		589		4,234					(61)		(5)	(962)
BALANCE (in shares) at Sep. 30, 2014				235,488,094
BALANCE at Mar. 31, 2014		11,004		589		4,234		7,209			(61)			(962)
BALANCE at Mar. 31, 2014	12,426		32				8,515		(1,032)	(61)		(21)
BALANCE (in shares) at Mar. 31, 2014			292,924,052	235,488,094					23,158,544
Net income for common stock	212						212
NET INCOME		172						172
Common stock dividends	(184)	(178)					(184)	(178)
Issuance of common shares for stock plans, net of repurchases (in shares)			(45,658)
Issuance of common shares for stock plans, net of repurchases (in shares)									45,658
Other comprehensive income	1	0										1
BALANCE at Jun. 30, 2014	12,455		32		4,993		8,543		(1,032)	(61)		(20)
BALANCE at Jun. 30, 2014		10,998		589		4,234		7,203			(61)		(5)	(962)
BALANCE (in shares) at Jun. 30, 2014			292,878,394	235,488,094					23,204,202
Net income for common stock	436	399					436
NET INCOME	436	399						399
Common stock dividends	(185)	(178)					(185)	(178)
Issuance of common shares for stock plans, net of repurchases (in shares)			(6,426)
Issuance of common shares for stock plans, net of repurchases (in shares)									6,426
Other comprehensive income	1											1
Noncontrolling interest	9														9
BALANCE at Sep. 30, 2014	12,716		32		4,993		8,794		(1,032)	(61)		(19)			9
BALANCE at Sep. 30, 2014	$ 12,707	$ 11,219		$ 589		$ 4,234		$ 7,424			$ (61)		$ (5)	$ (962)
BALANCE (in shares) at Sep. 30, 2014			292,871,968	235,488,094					23,210,628