Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Operating Leases
2021	$ 77
2022	74
2023	72
2024	72
2025	72
All years thereafter	983
Total future minimum lease payments	1,350
Less: imputed interest	(474)
Total	876
Operating lease liabilities (current)	77	$ 65
Operating lease liabilities (noncurrent)	799	809
Total	876
Finance Leases
2021	0
2022	0
2023	0
2024	0
2025	0
All years thereafter	1
Total future minimum lease payments	1
Less: imputed interest	0
Total	1
Other noncurrent liabilities	1
Total	1
CECONY
Operating Leases
2021	59
2022	56
2023	54
2024	54
2025	55
All years thereafter	499
Total future minimum lease payments	777
Less: imputed interest	(170)
Total	607
Operating lease liabilities (current)	59	54
Operating lease liabilities (noncurrent)	548	$ 551
Total	607
Finance Leases
2021	0
2022	0
2023	0
2024	0
2025	0
All years thereafter	0
Total future minimum lease payments	0
Less: imputed interest	0
Total	0
Other noncurrent liabilities	0
Total	$ 0