Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Operating Leases
2021	$ 79
2022	74
2023	73
2024	73
2025	74
All years thereafter	990
Total future minimum lease payments	1,363
Less: imputed interest	(466)
Total	897
Operating lease liabilities (current)	90	$ 65
Operating lease liabilities (noncurrent)	807	809
Total	897
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
Other noncurrent liabilities	2
Other current liabilities	1
Total	3
CECONY
Operating Leases
2021	60
2022	56
2023	55
2024	56
2025	57
All years thereafter	501
Total future minimum lease payments	785
Less: imputed interest	(162)
Total	623
Operating lease liabilities (current)	69	54
Operating lease liabilities (noncurrent)	554	$ 551
Total	623
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
Other noncurrent liabilities	1
Other current liabilities	1
Total	$ 2