Income Tax - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended			9 Months Ended
	Mar. 01, 2023	Oct. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)			$ 144,000,000		$ 160,000,000	$ 416,000,000	$ 330,000,000
Gain (Loss) on sale of the Clean Energy Businesses			(1,000,000)		$ 0	$ 866,000,000	$ 0
Gain on sale of subsidiary	$ 866,000,000
Gain on sale of subsidiary, after tax	$ 784,000,000
Increase (decrease) in accumulated deferred tax liabilities			228,000,000
Increase (decrease) in income taxes payable			$ (228,000,000)
State income tax, net of federal income tax benefit (in percent)			8.00%		6.00%	5.00%	6.00%
Estimated liability for uncertain tax positions			$ 10,000,000			$ 10,000,000
Research and development credits						2,000,000
Reduction of uncertain tax positions			12,000,000
Effective income tax rate reconciliation, uncertainty of taxes						9,000,000
Penalties recognized for uncertain tax positions						0	$ 0
Subsequent Event
Income Taxes Disclosure [Line Items]
Interest paid		$ 6,000,000
Income taxes paid		4,000,000
Special deposit		$ 12,000,000
State and Local Jurisdiction | New York State Division of Taxation and Finance
Income Taxes Disclosure [Line Items]
Expected minimum loss						$ 5,000,000
State income tax, net of federal income tax benefit (in percent)						7.25%
State and Local Jurisdiction | Metropolitan Transportation Authority Subcharge
Income Taxes Disclosure [Line Items]
State income tax, net of federal income tax benefit (in percent)						9.425%
CECONY
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)			109,000,000		$ 124,000,000	$ 297,000,000	232,000,000
Increase (decrease) in accumulated deferred tax liabilities			204,000,000
Increase (decrease) in income taxes payable			(204,000,000)
Reversal of uncertain tax positions						4,000,000
CECONY | Subsidiaries
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)			$ 109,000,000		$ 124,000,000	$ 297,000,000	$ 232,000,000
State income tax, net of federal income tax benefit (in percent)			5.00%		5.00%	5.00%	5.00%
Increase in accumulated deferred tax liabilities				$ 10,000,000
Estimated liability for uncertain tax positions			$ 7,000,000			$ 7,000,000
Effective income tax rate reconciliation, uncertainty of taxes						5,000,000
Clean Energy Businesses
Income Taxes Disclosure [Line Items]
Gain (Loss) on sale of the Clean Energy Businesses						214,000,000
Renewable energy tax credits			13,000,000			13,000,000
COVID-19 assistance for uncollectible accounts			19,000,000			19,000,000
Deferred tax assets, tax credits			$ 105,000,000			105,000,000
Deferred state taxes benefit						$ 27,000,000