Income Tax - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 23	$ 17	$ 14
Additions based on tax positions related to the current year	8	3	3
Additions based on tax positions of prior years	3	6	2
Reductions for tax positions of prior years	(11)	(1)	(2)
Settlements	(12)	(2)	0
Balance at end of period	11	23	17
CECONY
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	8	5	3
Additions based on tax positions related to the current year	4	2	2
Additions based on tax positions of prior years	1	1	1
Reductions for tax positions of prior years	(6)	0	(1)
Settlements	0	0	0
Balance at end of period	$ 7	$ 8	$ 5