Mergers, Acquisitions, and Dispositions - Assets Disposition Table (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Electricity Generation Plant, Non-Nuclear [Member]
Assets Disposition Table [Line Items]
Property, plant and equipment, net (a)			$ 617	[1]
Inventory			31
Current assets			1
Total assets held for sale	649	14	649
Accounts payable			1
Accrued expenses	1,462	1,633	4
Other current liabilities	985	858	13
Total liabilities held for sale (b)			18	[2]
Asset Impairment Charges			$ 50

[1] The total aggregate book value of property, plant and equipment is net of a $50 million pre-tax impairment loss recorded within Operating and maintenance expense on Exelon’s and Generation’s Statements of Operations and Comprehensive Income. See Note 7 - Impairment of Long-Lived Assets for further information.

[2] Included within Other current liabilities on Exelon's and Generation's Consolidated Balance Sheets.