Early Nuclear Plant Retirements Early Plant Retirement Pretax Expense (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Nuclear Fuel Amortization	[1]			$ 862	$ 841
Depreciation	[2]			2,490	1,648
Other, net		$ 120	$ (244)	377	$ (179)
Nuclear Plant [Member]
Nuclear Fuel Amortization				37
Depreciation				459
Accretion Expense, Including Asset Retirement Obligations				2
Other, net				(55)
Other Expenses				$ 443

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

[2] (a)Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income.