Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Assets under finance leases	$ 2		$ 2		$ 2
Finance leases, accumulated amortization	4		4
Right-of-use assets	$ 2	$ 1	46	$ 18
Operating lease payment, not yet commenced			$ 3
Operating lease, not yet commenced, term of contract	40 years		40 years
CECONY | Subsidiaries
Lessee, Lease, Description [Line Items]
Assets under finance leases	$ 1		$ 1		$ 1
Finance leases, accumulated amortization	2		2
Right-of-use assets	$ 1	$ 0	$ 1	$ 1