Income Taxes Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current - U.S. Federal	$ 116	$ 10	$ (91)
International	1	0	3
Total current	117	10	(88)
Deferred - U.S. Federal	866	(173)	377
International	2	(3)	0
Total deferred	868	(176)	377
Total income tax expense (benefit)	$ 985	$ (166)	$ 289