Early Nuclear Plant Retirements Early Nuclear Plant Retirements (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross			$ 1,274	$ 1,104
Property, plant and equipment, net			71,555	57,439
Nuclear Fuel Amortization	[1]		1,159	1,116	$ 1,073
Asset Retirement Obligation, Accretion Expense	[2]		446	398	345
Property, plant and equipment			3,477	2,227	2,080
Other Nonoperating Income (Expense)			413	(46)	455
Facility Closing [Member]
Property, Plant and Equipment [Line Items]
Other Expenses			688
Quad Cities [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross			39
Nuclear Fuel, Net of Amortization			83
Construction work in progress			37
Asset Retirement Obligation			(565)
Property, plant and equipment, net			1,015
Nuclear Plant [Member]
Property, Plant and Equipment [Line Items]
Other Expenses			688
Nuclear Fuel Amortization			60
Asset Retirement Obligation, Accretion Expense			2
Property, plant and equipment		$ 146	712
Other Nonoperating Income (Expense)			(86)
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross			935	880
Property, plant and equipment, net			25,585	25,843
Nuclear Fuel Amortization	[1]		1,159	1,116	1,073
Asset Retirement Obligation, Accretion Expense	[2]		446	397	345
Property, plant and equipment			1,835	1,007	922
Other Nonoperating Income (Expense)			$ 401	$ (60)	$ 406

[1] Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income.

[2] Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income.