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, 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
Beginning Balance at Dec. 31, 2018									$ 12,910	$ 589	$ 4,769	$ 8,581	$ (962)	$ (62)	$ (5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	445			424				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
Ending Balance at Mar. 31, 2019									13,319	$ 589	4,994	8,765	(962)	(62)	(5)
Beginning Balance (shares) at Dec. 31, 2019		333			23
Beginning Balance (shares) at Dec. 31, 2019										235
Beginning Balance at Dec. 31, 2019	18,213	$ 35	8,054	11,100	$ (1,038)	(110)	(19)	191
Beginning Balance at Dec. 31, 2019	18,022								14,147	$ 589	5,669	8,919	(962)	(62)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	392			375				17
Net income	375								406			406
Common stock dividends	(255)			(255)					(246)			(246)
Issuance of common shares – public offering (shares)		1
Issuance of common shares - public offering	88		88
Issuance of common shares for stock plans	26		26
Capital contribution by parent									25		25
Other comprehensive income	5						5		1						1
Distributions to noncontrolling interest	(2)							(2)
Ending Balance (shares) at Mar. 31, 2020		334			23
Ending Balance (shares) at Mar. 31, 2020										235
Ending Balance at Mar. 31, 2020	18,467	$ 35	$ 8,168	$ 11,220	$ (1,038)	$ (110)	$ (14)	$ 206
Ending Balance at Mar. 31, 2020	$ 18,261								$ 14,333	$ 589	$ 5,694	$ 9,079	$ (962)	$ (62)	$ (5)