Summary of Significant Accounting Policies and Other Matters - Long-Lived and Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net		$ 1,219,000,000
Amortization of intangible assets		71,000,000	$ 95,000,000
Amortization expense, year 1	$ 0
Amortization expense, year 2	0
Amortization expense, year 3	0
Amortization expense, year 4	0
Amortization expense, year 5	0
Impairment charges	0	0	$ 0
Power Purchase Agreements
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization		359,000,000
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net		2,000,000
Accumulated amortization		9,000,000
Other Intangible Assets | CECONY
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 0	$ 0