Summary of Significant Accounting Policies and Other Matters - Schedule of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	May 31, 2021	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Supplemental retirement income plan assets	$ 524	$ 459
Deferred income plan assets	99	93
Other	3	2
Total investments	$ 999	841
NY Transco | Payment Guarantee by CET Electric of Contributions to New York Transco LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest, percentage	45.70%
NY Transco - Propel NY Energy Project | Payment Guarantee by CET Electric of Contributions to New York Transco LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest, percentage	41.70%
CECONY
Schedule of Equity Method Investments [Line Items]
Supplemental retirement income plan assets	$ 502	439
Deferred income plan assets	99	93
Other	7	7
Total investments	608	539
Mountain Valley Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investment	530	530
Mountain Valley Pipeline | CET Gas
Schedule of Equity Method Investments [Line Items]
Equity method investment				$ 530
Aggregate project cost			$ 7,200
Mountain Valley Pipeline | Con Edison Transmission
Schedule of Equity Method Investments [Line Items]
Equity method investment	144	111
Mountain Valley Pipeline | Con Edison Transmission | CECONY
Schedule of Equity Method Investments [Line Items]
Equity method investment	0	0
New York Transco, LLC | Con Edison Transmission
Schedule of Equity Method Investments [Line Items]
Equity method investment	221	176
New York Transco, LLC | Con Edison Transmission | CECONY
Schedule of Equity Method Investments [Line Items]
Equity method investment	0	0
Virginia Tax Equity Project
Schedule of Equity Method Investments [Line Items]
Equity method investment	8	0
Virginia Tax Equity Project | CECONY
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 0	$ 0