Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
2021	$ 79
2022	77
2023	74
2024	75
2025	75
All years thereafter	938
Total future minimum lease payments	1,318
Less: imputed interest	(458)
Total	860
Operating lease liabilities (current)	96	$ 65
Operating lease liabilities (noncurrent)	764	809
Total	860
Finance Leases
2021	1
2022	1
2023	0
2024	0
2025	0
All years thereafter	1
Total future minimum lease payments	3
Less: imputed interest	0
Total	3
Other current liabilities	1
Other noncurrent liabilities	2
Total	3
CECONY
Operating Leases
2021	62
2022	58
2023	57
2024	57
2025	58
All years thereafter	451
Total future minimum lease payments	743
Less: imputed interest	(158)
Total	585
Operating lease liabilities (current)	73	54
Operating lease liabilities (noncurrent)	512	$ 551
Total	585
Finance Leases
2021	1
2022	1
2023	0
2024	0
2025	0
All years thereafter	0
Total future minimum lease payments	2
Less: imputed interest	0
Total	2
Other current liabilities	1
Other noncurrent liabilities	1
Total	$ 2