Leases - Lease Cost and Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 17	$ 17	$ 34	$ 37
Operating lease cash flows	4	4	9	11
CECONY | Subsidiaries
Lessee, Lease, Description [Line Items]
Operating lease cost	16	16	33	33
Operating lease cash flows	$ 4	$ 4	$ 7	$ 8