Consolidated Statement of Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Capital Stock Expense	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling 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)
BALANCE AS OF BEGINNING OF PERIOD (in shares) at Dec. 31, 2017		310,000,000								235,000,000
BALANCE AS OF BEGINNING OF PERIOD at Dec. 31, 2017	$ 15,425	$ 34	$ 6,298	$ 10,235	$ (1,038)	$ (85)	$ (26)	$ 7
BALANCE AS OF BEGINNING OF PERIOD at Dec. 31, 2017									$ 12,439	$ 589	$ 4,649	$ 8,231	$ (962)	$ (62)	$ (6)
TREASURY STOCK, BALANCE AS OF BEGINNING OF PERIOD (in shares) at Dec. 31, 2017					23,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,382								1,196			1,196
Net Income	1,382			1,382
Common stock dividends	(889)			(889)					(846)			(846)
Issuance of common shares - public offering (in shares)		11,000,000
Issuance of common shares - public offering	705		719			(14)
Issuance of common shares for stock plans	100		100
Capital contribution by parent									120		120
Other comprehensive income	10						10		1						1
Noncontrolling interest	106							106
BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2018		321,000,000								235,000,000
BALANCE AS OF END OF PERIOD at Dec. 31, 2018	16,839	$ 34	7,117	10,728	$ (1,038)	(99)	(16)	113
BALANCE AS OF END OF PERIOD at Dec. 31, 2018									12,910	$ 589	4,769	8,581	(962)	(62)	(5)
TREASURY STOCK, BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2018					23,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,343								1,250			1,250
Net Income	1,440			1,343				97
Common stock dividends	(971)			(971)					(912)			(912)
Issuance of common shares - public offering (in shares)		12,000,000
Issuance of common shares - public offering	825	$ 1	835			(11)
Issuance of common shares for stock plans	102		102
Capital contribution by parent									900		900
Other comprehensive income	(3)						(3)		$ (1)						(1)
Noncontrolling interest	$ (19)							(19)
BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2019	332,629,597	333,000,000							235,488,094	235,000,000
BALANCE AS OF END OF PERIOD at Dec. 31, 2019	$ 18,213	$ 35	8,054	11,100	$ (1,038)	(110)	(19)	191
BALANCE AS OF END OF PERIOD at Dec. 31, 2019	18,022								$ 14,147	$ 589	5,669	8,919	(962)	(62)	(6)
TREASURY STOCK, BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2019					23,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,101								1,185			1,185
Net Income	1,144			1,101				43
Common stock dividends	(1,023)			(1,023)					(982)			(982)
Issuance of common shares - public offering (in shares)		9,000,000
Issuance of common shares - public offering	640	$ 1	641			(2)
Issuance of common shares for stock plans	113		113
Capital contribution by parent									500		500
Other comprehensive income	(6)						(6)		$ (1)						(1)
Noncontrolling interest	$ (16)							(16)
BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2020	342,297,534	342,000,000							235,488,094	235,000,000
BALANCE AS OF END OF PERIOD at Dec. 31, 2020	$ 19,065	$ 36	$ 8,808	$ 11,178	$ (1,038)	$ (112)	$ (25)	$ 218
BALANCE AS OF END OF PERIOD at Dec. 31, 2020	$ 18,847								$ 14,849	$ 589	$ 6,169	$ 9,122	$ (962)	$ (62)	$ (7)
TREASURY STOCK, BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2020					23,000,000