Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 2,076	$ 2,157
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	465
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	802
Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	739
Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	70
0 – 3 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,328
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	465
0 – 3 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	478
0 – 3 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	315
0 – 3 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	70
4 – 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	78
4 – 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	30
4 – 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	48
4 – 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	670
Greater than 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	294
Greater than 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	376
Greater than 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 0