Leases - Future Minimum Lease Payments (Details) $ in Millions	Sep. 30, 2019 USD ($)
Operating Leases
2020	$ 74
2021	73
2022	69
2023	69
2024	69
All years thereafter	966
Total future minimum lease payments	1,320
Less: imputed interest	(442)
Total	878
Operating lease liabilities (current)	59
Operating lease liabilities (noncurrent)	819
Total	878
Finance Leases
2020	1
2021	0
2022	0
2023	0
2024	0
All years thereafter	1
Total future minimum lease payments	2
Less: imputed interest	0
Total	2
Other current liabilities	1
Other noncurrent liabilities	1
Total	2
CECONY
Operating Leases
2020	58
2021	57
2022	53
2023	53
2024	53
All years thereafter	550
Total future minimum lease payments	824
Less: imputed interest	(180)
Total	644
Operating lease liabilities (current)	49
Operating lease liabilities (noncurrent)	595
Total	644
Finance Leases
2020	1
2021	0
2022	0
2023	0
2024	0
All years thereafter	0
Total future minimum lease payments	1
Less: imputed interest	0
Total	1
Other current liabilities	1
Other noncurrent liabilities	0
Total	$ 1