Consolidated Statement of Equity/Shareholder's Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Capital Stock Expense	Accumulated Other Comprehensive Income/(Loss)	Non- controlling Interest	CECONY	CECONY Common Stock	CECONY Additional Paid-In Capital	CECONY Retained Earnings	CECONY Repurchased Con Edison Stock	CECONY Capital Stock Expense	CECONY Accumulated Other Comprehensive Income/(Loss)
Beginning Balance (shares) at Dec. 31, 2017		310			23
Beginning Balance (shares) at Dec. 31, 2017										235
Beginning Balance at Dec. 31, 2017	$ 15,425	$ 34	$ 6,298	$ 10,235	$ (1,038)	$ (85)	$ (26)	$ 7							$ (6)
Beginning Balance at Dec. 31, 2017									$ 12,439	$ 589	$ 4,649	$ 8,231	$ (962)	$ (62)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	428			428
Net income	0
Net income	428								389			389
Common stock dividends	(221)			(221)					(211)			(211)
Issuance of common shares for stock plans (shares)		1
Issuance of common shares for stock plans	25		25
Capital contribution by parent									45		45
Other comprehensive income	4						4		0
Distributions to noncontrolling interest	0
Ending Balance (shares) at Mar. 31, 2018		311			23
Ending Balance (shares) at Mar. 31, 2018										235
Ending Balance at Mar. 31, 2018	15,661	$ 34	6,323	10,442	$ (1,038)	(85)	(22)	7							(6)
Ending Balance at Mar. 31, 2018									12,662	$ 589	4,694	8,409	(962)	(62)	(6)
Beginning Balance (shares) at Dec. 31, 2018		321			23
Beginning Balance (shares) at Dec. 31, 2018										235
Beginning Balance at Dec. 31, 2018	16,839	$ 34	7,117	10,728	$ (1,038)	(99)	(16)	113							(5)
Beginning Balance at Dec. 31, 2018	16,726								12,910	$ 589	4,769	8,581	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	445			424
Net income	21							21
Net income	424								412			412
Common stock dividends	(237)			(237)					(228)			(228)
Issuance of common shares – public offering (shares)		6
Issuance of common shares – public offering	425		433			(8)
Issuance of common shares for stock plans	27		27
Capital contribution by parent									225		225
Other comprehensive income	4						4		0
Distributions to noncontrolling interest	(2)							(2)
Ending Balance (shares) at Mar. 31, 2019		327			23
Ending Balance (shares) at Mar. 31, 2019										235
Ending Balance at Mar. 31, 2019	17,501	$ 34	$ 7,577	$ 10,915	$ (1,038)	$ (107)	$ (12)	$ 132							(5)
Ending Balance at Mar. 31, 2019	$ 17,369								$ 13,319	$ 589	$ 4,994	$ 8,765	$ (962)	$ (62)	$ (5)