Income Tax - Additional Information (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Mar. 01, 2023	Oct. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Increase to net deferred income tax liabilities			$ 228
Effective income tax rate reconciliation, increase (decrease), percent (in percent)			(8.00%)
Gain (loss) on disposition of stock in subsidiary	$ 865
Gain (loss) on disposition of stock in subsidiary, after tax	$ 767
Deferred tax asset, valuation allowance			$ 7	$ 18
Increase (decrease) in income taxes payable			$ (228)
State income tax rate (in percent)			5.00%	6.00%	4.00%
Unrecognized tax benefits			$ 11	$ 23	$ 17	$ 14
Additions based on tax positions related to the current year			8	3	$ 3
Unrecognized tax benefits, increase (decrease) resulting from prior period tax positions			(8)
Effective income tax rate reconciliation, uncertainty of taxes			3
Unrecognized tax benefits, period increase (decrease)			(12)
Unrecognized tax benefits, net			10
Dividends and interest paid		$ 6
Income taxes paid		4
Deposit applied to income taxes		$ 12
Clean Energy Businesses
Operating Loss Carryforwards [Line Items]
Deferred tax assets			17
Deferred tax asset, valuation allowance			9
Deferred tax assets, operating loss carryforwards, state and local			26
General Business Tax Credit
Operating Loss Carryforwards [Line Items]
Tax credit carryovers			270
State | New York State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards				43
Deferred tax asset, valuation allowance				9
Expected taxable income minimum			$ 5
State income tax rate (in percent)			7.25%
State | New York City
Operating Loss Carryforwards [Line Items]
Deferred tax assets			$ 8
State | Metropolitan Transportation Authority Subcharge
Operating Loss Carryforwards [Line Items]
State income tax rate (in percent)			9.425%
CECONY
Operating Loss Carryforwards [Line Items]
Increase to net deferred income tax liabilities			$ 204
Deferred tax asset, valuation allowance			0	$ 0
Increase (decrease) in income taxes payable			$ (204)
State income tax rate (in percent)			5.00%	5.00%	5.00%
Unrecognized tax benefits			$ 7	$ 8	$ 5	$ 3
Additions based on tax positions related to the current year			4	$ 2	$ 2
Uncertain tax positions, reversed			6
CECONY | Subsidiaries
Operating Loss Carryforwards [Line Items]
Increase (decrease) in deferred tax liabilities			10
Unrecognized tax benefits			7
Additions based on tax positions related to the current year			4
Unrecognized tax benefits, increase (decrease) resulting from prior period tax positions			$ (5)