Income Tax - Schedule of Components of Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
State
Current	$ 14	$ 7	$ (12)
Deferred	79	50	96
Federal
Current	43	(2)	0
Deferred	61	42	219
Amortization of investment tax credits	(7)	(7)	(7)
Total income tax expense	190	90	296
CECONY
State
Current	1	6	22
Deferred	106	97	68
Federal
Current	121	41	185
Deferred	21	73	63
Amortization of investment tax credits	(3)	(2)	(3)
Total income tax expense	$ 246	$ 215	$ 335