Leases - Lease Cost and Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 17	$ 22	$ 37	$ 44
Operating lease cash flows	4	8	11	17
CECONY | Subsidiaries
Lessee, Lease, Description [Line Items]
Operating lease cost	16	17	33	33
Operating lease cash flows	$ 4	$ 4	$ 8	$ 8