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]
BALANCE at Dec. 31, 2012	$ 11,869	$ 10,552	$ 32	$ 589	$ 4,991	$ 4,234	$ 7,997	$ 6,761	$ (1,037)	$ (61)	$ (61)	$ (53)	$ (9)	$ (962)
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 dividend to parent	(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, repurchases (In Shares)									(95,468)
Other comprehensive income	3	0										3	0
BALANCE at Mar. 31, 2013	11,889	10,647	32	589	4,989	4,234	8,009	6,856	(1,030)	(61)	(61)	(50)	(9)	(962)
BALANCE (In Shares) at Mar. 31, 2013			292,967,364	235,488,094					23,115,232
BALANCE at Dec. 31, 2012	11,869	10,552		589		4,234				(61)	(61)			(962)
BALANCE (In Shares) at Dec. 31, 2012				235,488,094
Net income for common stock	364	430
NET INCOME	364	430
BALANCE at Jun. 30, 2013	11,883	10,618		589		4,234				(61)	(61)			(962)
BALANCE (In Shares) at Jun. 30, 2013				235,488,094
BALANCE at Mar. 31, 2013	11,889	10,647	32	589	4,989	4,234	8,009	6,856	(1,030)	(61)	(61)	(50)	(9)	(962)
BALANCE (In Shares) at Mar. 31, 2013			292,967,364	235,488,094					23,115,232
Net income for common stock	172	153					172
NET INCOME	172	153						153
Common stock dividend to parent	(180)	(182)					(180)	(182)
Issuance of common shares for stock plans, net of repurchases	0				1				(1)
Issuance of common shares for stock plans, net of repurchases (In Shares)			(4,078)
Issuance of common shares for stock plans, repurchases (In Shares)									4,078
Other comprehensive income	2	0										2	0
BALANCE at Jun. 30, 2013	11,883	10,618	32	589	4,990	4,234	8,001	6,827	(1,031)	(61)	(61)	(48)	(9)	(962)
BALANCE (In Shares) at Jun. 30, 2013			292,963,286	235,488,094					23,119,310
BALANCE at Dec. 31, 2013	12,245	10,847	32	589	4,995	4,234	8,338	7,053	(1,034)	(61)	(61)	(25)	(6)	(962)
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 dividend to parent	(184)	(178)					(184)	(178)
Issuance of common shares for stock plans, net of repurchases	0				(2)				2
Issuance of common shares for stock plans, net of repurchases (In Shares)			51,656
Issuance of common shares for stock plans, repurchases (In Shares)									(51,656)
Other comprehensive income	4	1										4	1
BALANCE at Mar. 31, 2014	12,426	11,004	32	589	4,993	4,234	8,515	7,209	(1,032)	(61)	(61)	(21)	(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)	(61)			(962)
BALANCE (In Shares) at Dec. 31, 2013				235,488,094
Net income for common stock	574	506
NET INCOME	574	506
BALANCE at Jun. 30, 2014	12,455	10,998		589	4,993	4,234				(61)	(61)		(5)	(962)
BALANCE (In Shares) at Jun. 30, 2014				235,488,094
BALANCE at Mar. 31, 2014	12,426	11,004	32	589		4,234	8,515	7,209	(1,032)	(61)	(61)	(21)		(962)
BALANCE (In Shares) at Mar. 31, 2014			292,924,052	235,488,094					23,158,544
Net income for common stock	212	172					212
NET INCOME	212	172						172
Common stock dividend to parent	(184)	(178)					(184)	(178)
Issuance of common shares for stock plans, net of repurchases	0
Issuance of common shares for stock plans, net of repurchases (In Shares)			(45,658)
Issuance of common shares for stock plans, repurchases (In Shares)									45,658
Other comprehensive income	1	0										1
BALANCE at Jun. 30, 2014	$ 12,455	$ 10,998	$ 32	$ 589	$ 4,993	$ 4,234	$ 8,543	$ 7,203	$ (1,032)	$ (61)	$ (61)	$ (20)	$ (5)	$ (962)
BALANCE (In Shares) at Jun. 30, 2014			292,878,394	235,488,094					23,204,202