Material Contingencies - Total Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 2,157	$ 2,042
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	490
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	831
Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	766
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	1,348
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	490
0 – 3 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	469
0 – 3 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	319
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	88
4 – 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	37
4 – 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	51
4 – 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
> 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	721
> 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
> 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	325
> 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	396
> 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 0