Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Assets under finance leases	$ 2		$ 2
Finance leases, accumulated amortization	4		4
Right-of-use assets	44	$ 16
Lessee, Operating Lease, Lease Not Yet Commenced, Present Value Of Lease Payments	$ 6
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	45 years
CECONY | Subsidiaries
Lessee, Lease, Description [Line Items]
Assets under finance leases	$ 1		1
Finance leases, accumulated amortization	2		$ 2
Right-of-use assets	$ 1	$ 1