Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 2,067	$ 2,157
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	480
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	779
Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	738
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	1,309
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	480
0 – 3 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	456
0 – 3 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	303
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	90
4 – 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	31
4 – 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	59
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	668
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	292
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