Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Operating Leases
2022	$ 86
2023	76
2024	74
2025	75
2026	76
All years thereafter	947
Total future minimum lease payments	1,334
Less: imputed interest	(465)
Total	869
Operating lease liabilities (current)	106	$ 96
Operating lease liabilities (noncurrent)	763	764
Total	869
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 noncurrent liabilities	2
Other current liabilities	1
Total	3
CECONY
Operating Leases
2022	62
2023	58
2024	56
2025	57
2026	58
All years thereafter	449
Total future minimum lease payments	740
Less: imputed interest	(152)
Total	588
Operating lease liabilities (current)	78	73
Operating lease liabilities (noncurrent)	510	$ 512
Total	588
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 noncurrent liabilities	1
Other current liabilities	1
Total	$ 2