Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Operating Leases
2022	$ 84
2023	75
2024	74
2025	75
2026	75
All years thereafter	929
Total future minimum lease payments	1,312
Less: imputed interest	(453)
Total	859
Operating lease liabilities (current)	109	$ 96
Operating lease liabilities (noncurrent)	750	764
Total	859
Finance Leases
2022	1
2023	1
2024	0
2025	0
2026	0
All years thereafter	1
Total future minimum lease payments	3
Less: imputed interest	0
Other current liabilities	1
Other noncurrent liabilities	2
Total	3
Subsidiaries
Operating Leases
Operating lease liabilities (current)	82	73
Operating lease liabilities (noncurrent)	507	$ 512
CECONY | Subsidiaries
Operating Leases
2022	61
2023	57
2024	57
2025	58
2026	58
All years thereafter	448
Total future minimum lease payments	739
Less: imputed interest	(150)
Total	589
Operating lease liabilities (current)	82
Operating lease liabilities (noncurrent)	507
Total	589
Finance Leases
2022	1
2023	1
2024	0
2025	0
2026	0
All years thereafter	0
Total future minimum lease payments	2
Less: imputed interest	0
Other current liabilities	1
Other noncurrent liabilities	1
Total	$ 2