Federal Income Taxes (Federal Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income tax expense (benefit), continuing operations [Abstract]
Current	$ 88	$ 212	$ 220
Deferred	178	64	263
Federal income tax expense (benefit)	266	276	483
Parent Company [Member]
Income tax expense (benefit), continuing operations [Abstract]
Federal income tax expense (benefit)	$ (95)	$ (66)	$ (77)