Income Taxes Income Taxes - Other Income Tax Matters (Details) - State and Local Jurisdiction [Member]	3 Months Ended
Sep. 30, 2019 USD ($)
Schedule of Components of Income Tax Expense (Benefit) [Line Items]
Increase (Decrease) in Deferred Income Taxes	$ 23
Increase (Decrease) in Income Taxes	23
Exelon Generation Co L L C [Member]
Schedule of Components of Income Tax Expense (Benefit) [Line Items]
Increase (Decrease) in Deferred Income Taxes	9
Increase (Decrease) in Income Taxes	$ 9

[Line Items] for Schedule of Components of Income Tax Expense (Benefit) [Table]

No definition available.

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- Definition

The increase (decrease) during the reporting period in the account that represents the temporary difference that results from Income or Loss that is recognized for accounting purposes but not for tax purposes and vice versa.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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- Definition

The increase (decrease) during the reporting period in the amounts payable to taxing authorities for taxes that are based on the reporting entity's earnings, net of amounts receivable from taxing authorities for refunds of overpayments or recoveries of income taxes, and in deferred and other tax liabilities and assets.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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