Income Tax - Schedule of Components of Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
State
Current	$ 179	$ 5	$ 14
Deferred	6	324	79
Federal
Current	176	58	43
Deferred	237	117	61
Amortization of investment tax credits	(111)	(6)	(7)
Total income tax expense	487	498	190
CECONY
State
Current	(102)	0	1
Deferred	246	110	106
Federal
Current	(95)	170	121
Deferred	311	(23)	21
Amortization of investment tax credits	(2)	(2)	(3)
Total income tax expense	$ 358	$ 255	$ 246