Leases - Lease Cost and Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 70	$ 88	$ 86
Operating lease cash flows	68	83	80
CECONY
Lessee, Lease, Description [Line Items]
Operating lease cost	66	67	66
Operating lease cash flows	$ 65	$ 64	$ 63