Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Operating Leases
2020	$ 79
2021	74
2022	71
2023	69
2024	68
All years thereafter	973
Total future minimum lease payments	1,334
Less: imputed interest	(459)
Total	875
Operating lease liabilities (current)	50	$ 0
Operating lease liabilities (noncurrent)	825	0
Total	875
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	58
2022	55
2023	53
2024	53
All years thereafter	553
Total future minimum lease payments	830
Less: imputed interest	(191)
Total	639
Operating lease liabilities (current)	41	0
Operating lease liabilities (noncurrent)	598	$ 0
Total	639
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