Early Nuclear Plant Retirements Early Nuclear Plant Retirements table (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015
Property, Plant and Equipment [Line Items]
Nuclear Fuel Amortization	[1]	$ 557	$ 552
Asset Retirement Obligation, Accretion Expense	[2]	220	193
Depreciation	[3]	1,432	$ 1,087
Facility Closing [Member]
Property, Plant and Equipment [Line Items]
Other Expenses		$ 110

[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

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