Income Tax - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)	$ 153	$ 78
Estimated liability for uncertain tax positions	16
Effective income tax rate reconciliation, uncertainty of taxes	12
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate	16
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate, net of federal taxes	15
Subsidiaries
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)	117	114
CECONY | Subsidiaries
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)	117	$ 114
Estimated liability for uncertain tax positions	5
Effective income tax rate reconciliation, uncertainty of taxes	3
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate	$ 5