Income Tax - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 14	$ 13	$ 6
Additions based on tax positions related to the current year	3	0	1
Additions based on tax positions of prior years	2	1	10
Reductions for tax positions of prior years	(2)	0	(2)
Reductions from expiration of statute of limitations	0	0	0
Settlements	0	0	(2)
Balance at end of period	17	14	13
CECONY
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	3	2	4
Additions based on tax positions related to the current year	2	0	1
Additions based on tax positions of prior years	1	1	0
Reductions for tax positions of prior years	(1)	0	(1)
Reductions from expiration of statute of limitations	0	0	0
Settlements	0	0	(2)
Balance at end of period	$ 5	$ 3	$ 2