Derivative Financial Instruments - Summary of Cash Collateral and Letters of Credit (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
---|---|---|
Derivative Instruments, Gain (Loss) [Line Items] | ||
Derivative, Collateral, Right to Reclaim Cash | $ 511 | $ 982 |
Derivative, Collateral, Right to Reclaim Securities | 226 | 264 |
Derivative, Collateral, Obligation to Return Cash | 110 | 103 |
Derivative, Collateral, Obligation to Return Securities | 40 | 112 |
Incremental Collateral For Loss Of Investment Grade Credit Rating | 1,432 | 1,509 |
Exelon Generation Co L L C [Member] | ||
Derivative Instruments, Gain (Loss) [Line Items] | ||
Derivative, Collateral, Right to Reclaim Cash | 511 | 982 |
Derivative, Collateral, Right to Reclaim Securities | 226 | 264 |
Derivative, Collateral, Obligation to Return Cash | 110 | 103 |
Derivative, Collateral, Obligation to Return Securities | 40 | 112 |
Incremental Collateral For Loss Of Investment Grade Credit Rating | $ 1,432 | $ 1,509 |