Income Tax - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Increase to net deferred income tax liabilities		$ 457
Deferred tax asset, valuation allowance	$ 12	7
Increase (decrease) in income taxes payable		$ (457)
State income tax rate (in percent)	5.00%	5.00%	6.00%
Accrued income taxes	$ 139
Unrecognized tax benefits	9	$ 11	$ 23	$ 17
Additions based on tax positions related to the current year	4	8	$ 3
Unrecognized tax benefits, increase (decrease) resulting from prior period tax positions	(3)
Effective income tax rate reconciliation, uncertainty of taxes	1
Unrecognized tax benefits, period increase (decrease)	(3)
Unrecognized tax benefits, net	8
Clean Energy Businesses
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards, state and local	5
General Business Tax Credit
Operating Loss Carryforwards [Line Items]
Tax credit carryovers	346
State | New York State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	14
Deferred tax asset, valuation allowance	6
State | New York City
Operating Loss Carryforwards [Line Items]
Deferred tax assets	36
CECONY
Operating Loss Carryforwards [Line Items]
Increase to net deferred income tax liabilities		418
Deferred tax asset, valuation allowance	$ 0	0
Increase (decrease) in income taxes payable		$ (418)
State income tax rate (in percent)	5.00%	5.00%	5.00%
Accrued income taxes	$ 111
Unrecognized tax benefits	5	$ 7	$ 8	$ 5
Additions based on tax positions related to the current year	4	4	$ 2
CECONY | Subsidiaries
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits	$ 5
O&R
Operating Loss Carryforwards [Line Items]
Increase to net deferred income tax liabilities		39
Increase (decrease) in income taxes payable		$ (39)