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, 2016		305,000,000								235,000,000
BALANCE AS OF BEGINNING OF PERIOD at Dec. 31, 2016	$ 14,306	$ 33	$ 5,854	$ 9,559	$ (1,038)	$ (83)	$ (27)	$ 8							$ (7)
BALANCE AS OF BEGINNING OF PERIOD at Dec. 31, 2016									$ 11,829	$ 589	$ 4,347	$ 7,923	$ (962)	$ (61)	(7)
TREASURY STOCK, BALANCE AS OF BEGINNING OF PERIOD (in shares) at Dec. 31, 2016					23,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,525								1,104			1,104
Net Income	1,525			1,525
Common stock dividends	(849)			(849)					(796)			(796)
Issuance of common shares - public offering (in shares)		5,000,000
Issuance of common shares - public offering	343	$ 1	344			(2)
Issuance of common shares for stock plans	100		100
Capital contribution by parent									301		302			(1)
Other comprehensive income	1						1		1						1
Noncontrolling interest	(1)							(1)
BALANCE AS OF END OF PERIOD (in shares) at Dec. 31, 2017		310,000,000								235,000,000
BALANCE AS OF END OF PERIOD at Dec. 31, 2017	15,425	$ 34	6,298	10,235	$ (1,038)	(85)	(26)	7							(6)
BALANCE AS OF END OF PERIOD at Dec. 31, 2017									12,439	$ 589	4,649	8,231	(962)	(62)	(6)
TREASURY STOCK, BALANCE AS OF END 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	320,960,396	321,000,000								235,488,094
BALANCE AS OF END OF PERIOD at Dec. 31, 2018	$ 16,839	$ 34	7,117	10,728	$ (1,038)	(99)	(16)	113							(5)
BALANCE AS OF END OF PERIOD at Dec. 31, 2018	16,726								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							(6)
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