Consolidated Statement of Equity/Shareholder's Equity (Unaudited) - USD ($) $ in Millions	Total	CECONY	Common Stock	Common Stock CECONY	Additional Paid-In Capital	Additional Paid-In Capital CECONY	Retained Earnings	Retained Earnings CECONY	Repurchased Con Edison Stock CECONY	Treasury Stock	Capital Stock Expense	Capital Stock Expense CECONY	Accumulated Other Comprehensive Income/(Loss)	Accumulated Other Comprehensive Income/(Loss) CECONY	Noncontrolling Interest
Beginning Balance at Dec. 31, 2013	$ 12,245		$ 32		$ 4,995		$ 8,338			$ (1,034)	$ (61)		$ (25)
Beginning Balance at Dec. 31, 2013		$ 10,847		$ 589		$ 4,234		$ 7,053	$ (962)			$ (61)		$ (6)
Beginning Balance (in shares) at Dec. 31, 2013			292,872,396	235,488,094						23,210,200
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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							(51,656)
Other comprehensive income	4	1											4	1
Ending Balance at Mar. 31, 2014		11,004		$ 589		4,234		7,209	(962)			(61)		(5)
Ending Balance at Mar. 31, 2014	12,426		$ 32		4,993		8,515			$ (1,032)	(61)		(21)
Ending Balance (in shares) at Mar. 31, 2014			292,924,052	235,488,094						23,158,544
Beginning Balance at Dec. 31, 2013	12,245		$ 32		4,995		8,338			$ (1,034)	(61)		(25)
Beginning Balance at Dec. 31, 2013		10,847		$ 589		4,234		7,053	(962)			(61)		(6)
Beginning Balance (in shares) at Dec. 31, 2013			292,872,396	235,488,094						23,210,200
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for common stock	1,010	905
Net income	1,010	905
Ending Balance at Sep. 30, 2014		11,219		$ 589		4,234		7,424	(962)			(61)		(5)
Ending Balance at Sep. 30, 2014	12,716		$ 32		4,993		8,794			$ (1,032)	(61)		(19)		$ 9
Ending Balance (in shares) at Sep. 30, 2014			292,871,968	235,488,094						23,210,628
Beginning Balance at Mar. 31, 2014	12,426		$ 32		4,993		8,515			$ (1,032)	(61)		(21)
Beginning Balance at Mar. 31, 2014		11,004		$ 589		4,234		7,209	(962)			(61)		(5)
Beginning Balance (in shares) at Mar. 31, 2014			292,924,052	235,488,094						23,158,544
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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					0					$ 0
Issuance of common shares for stock plans, net of repurchases (in shares)			(45,658)							45,658
Other comprehensive income	1	0											1	0
Ending Balance at Jun. 30, 2014		10,998		$ 589		4,234		7,203	(962)			(61)
Ending Balance at Jun. 30, 2014	12,455		$ 32		4,993		8,543			$ (1,032)	(61)		(20)
Ending Balance (in shares) at Jun. 30, 2014			292,878,394	235,488,094						23,204,202
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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					0					$ 0
Issuance of common shares for stock plans, net of repurchases (in shares)			(6,426)							6,426
Other comprehensive income	1	0											1	0
Ending Balance at Sep. 30, 2014		11,219		$ 589		4,234		7,424	(962)			(61)		(5)
Ending Balance at Sep. 30, 2014	12,716		$ 32		4,993		8,794			$ (1,032)	(61)		(19)		9
Ending Balance (in shares) at Sep. 30, 2014			292,871,968	235,488,094						23,210,628
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interest	9														9
Noncontrolling interest	9
Beginning Balance at Dec. 31, 2014	12,585		$ 32		4,991		8,691			$ (1,032)	(61)		(45)		9
Beginning Balance at Dec. 31, 2014	12,576	11,188		$ 589		4,234		7,399	(962)			(61)		(11)
Beginning Balance (in shares) at Dec. 31, 2014			292,876,196	235,488,094						23,206,400
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for common stock	370						370
Net income		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	0											5	0
Ending Balance at Mar. 31, 2015		11,198		$ 589		4,234		7,409	(962)			(61)
Ending Balance at Mar. 31, 2015	12,770		$ 32		4,993		8,871			$ (1,034)	(61)		(40)		9
Ending Balance (in shares) at Mar. 31, 2015			292,900,796	235,488,094						23,181,800
Beginning Balance at Dec. 31, 2014	12,585		$ 32		4,991		8,691			$ (1,032)	(61)		(45)		9
Beginning Balance at Dec. 31, 2014	12,576	11,188		$ 589		4,234		7,399	(962)			(61)		(11)
Beginning Balance (in shares) at Dec. 31, 2014			292,876,196	235,488,094						23,206,400
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for common stock	1,017	935
Net income	1,017	935
Ending Balance at Sep. 30, 2015	13,040	11,430		$ 589		4,234		7,639	(962)			(61)		(9)
Ending Balance at Sep. 30, 2015	13,049		$ 32		5,008		9,137			$ (1,038)	(61)		(38)		9
Ending Balance (in shares) at Sep. 30, 2015			293,084,114	235,488,094						23,210,700
Beginning Balance at Mar. 31, 2015	12,770		$ 32		4,993		8,871			$ (1,034)	(61)		(40)		9
Beginning Balance at Mar. 31, 2015		11,198		$ 589		4,234		7,409	(962)			(61)
Beginning Balance (in shares) at Mar. 31, 2015			292,900,796	235,488,094						23,181,800
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for common stock	219						219
Net income		211						211
Common stock dividends	(190)	(178)					(190)	(178)
Issuance of common shares for stock plans, net of repurchases	(3)				0					$ (3)
Issuance of common shares for stock plans, net of repurchases (in shares)			(28,134)							28,134
Other comprehensive income	1	1											1	1
Ending Balance at Jun. 30, 2015		11,232		$ 589		4,234		7,442	(962)			(61)		(10)
Ending Balance at Jun. 30, 2015	12,797		$ 32		4,993		8,900			$ (1,037)	(61)		(39)		9
Ending Balance (in shares) at Jun. 30, 2015			292,872,662	235,488,094						23,209,934
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for common stock	428	375					428
Net income	428	375						375
Common stock dividends	(191)	(178)					(191)	(178)
Issuance of common shares for stock plans, net of repurchases	14				15					$ (1)
Issuance of common shares for stock plans, net of repurchases (in shares)			211,452							766
Other comprehensive income	1	1											1	1
Ending Balance at Sep. 30, 2015	13,040	$ 11,430		$ 589		$ 4,234		$ 7,639	$ (962)			$ (61)		$ (9)
Ending Balance at Sep. 30, 2015	13,049		$ 32		$ 5,008		$ 9,137			$ (1,038)	$ (61)		$ (38)		$ 9
Ending Balance (in shares) at Sep. 30, 2015			293,084,114	235,488,094						23,210,700
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interest	$ 9