Early Plant Retirements - Pretax Expense (Details) - Byron Dresden - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Asset Retirement Obligation, Revision of Estimate	$ (13)
Facility Closing [Member]
Accelerated depreciation	574	$ 254	$ 1,805	$ 254
Accelerated nuclear fuel amortization	42	14	148	14
Operating and maintenance	(94)	220	(94)	220
Asset Retirement Obligation, Revision of Estimate	(4)	(34)	(8)	(34)
Asset Retirement Obligation Contractual Offset	(60)	(129)	(451)	(129)
Restructuring and Related Cost, Incurred Cost	466	393	1,416	393
Exelon Generation Co L L C [Member]
Asset Retirement Obligation, Revision of Estimate	(13)
Exelon Generation Co L L C [Member] \| Facility Closing [Member]
Accelerated depreciation	574	254	1,805	254
Accelerated nuclear fuel amortization	42	14	148	14
Operating and maintenance	(94)	220	(94)	220
Asset Retirement Obligation, Revision of Estimate	(4)	(34)	(8)	(34)
Asset Retirement Obligation Contractual Offset	(60)	(129)	(451)	(129)
Restructuring and Related Cost, Incurred Cost	$ 466	$ 393	$ 1,416	$ 393

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- Definition

The amount of capitalized nuclear fuel costs that are charged to fuel expense during the period using the unit-of-production method.

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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The total amount of other operating cost and expense items that are associated with the entity's normal revenue producing operation.

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Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.

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Amount of accelerated depreciation charged against earnings associated with exit from or disposal of business activities or restructuring plan.

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