Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Operating Leases
2022	$ 82
2023	76
2024	75
2025	76
2026	75
All years thereafter	937
Total future minimum lease payments	1,321
Less: imputed interest	(452)
Total	869
Operating lease liabilities (current)	113	$ 96
Operating lease liabilities (noncurrent)	756	764
Total	869
Finance Leases
2022	1
2023	0
2024	0
2025	0
2026	0
All years thereafter	1
Total future minimum lease payments	2
Less: imputed interest	0
Other current liabilities	1
Other noncurrent liabilities	1
Total	2
Subsidiaries
Operating Leases
Operating lease liabilities (current)	85	73
Operating lease liabilities (noncurrent)	507	$ 512
CECONY | Subsidiaries
Operating Leases
2022	59
2023	58
2024	57
2025	58
2026	58
All years thereafter	446
Total future minimum lease payments	736
Less: imputed interest	(144)
Total	592
Operating lease liabilities (current)	85
Operating lease liabilities (noncurrent)	507
Total	592
Finance Leases
2022	1
2023	0
2024	0
2025	0
2026	0
All years thereafter	0
Total future minimum lease payments	1
Less: imputed interest	0
Other current liabilities	0
Other noncurrent liabilities	1
Total	$ 1