Implications of Potential Early Plant Retirements Implications of Potential Early Plant Retirements (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	$ 1,104	$ 1,024
Property, plant and equipment, net	57,439	52,170
Quad Cities [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	50
Nuclear Fuel, Net of Amortization	218
Construction work in progress	11
Asset Retirement Obligation	(698)
Property, plant and equipment, net	1,030
Clinton [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	57
Nuclear Fuel, Net of Amortization	107
Construction work in progress	9
Asset Retirement Obligation	(401)
Property, plant and equipment, net	579
Ginna [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	29
Nuclear Fuel, Net of Amortization	60
Construction work in progress	11
Asset Retirement Obligation	(644)
Property, plant and equipment, net	127
Nuclear Plant [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	136
Nuclear Fuel, Net of Amortization	385
Construction work in progress	31
Asset Retirement Obligation	(1,743)
Property, plant and equipment, net	1,736
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	880	847
Property, plant and equipment, net	$ 25,843	$ 23,028