Consolidated Statement of Changes in Shareholders Equity (Unaudited) (Parenthetical) (USD $) In Millions	6 Months Ended
Jun. 30, 2011
Exelon Generation Co L L C [Member]
Other comprehensive income, income taxes	$ 212
PECO Energy Co [Member] \| Accumulated Other Comprehensive (Loss) Income, Net
Other comprehensive income, income taxes	0
Accumulated Other Comprehensive (Loss) Income, Net
Other comprehensive income, income taxes	$ 52

Tax effect of the change in accumulated other comprehensive income, that is, the tax effect on items included in other comprehensive income during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 36
-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 24
-Subparagraph b

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 31
-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration