Income Taxes (Components of Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal:
Current	$ 0	$ 2	$ 9
Deferred	545	(361)	(63)
State:
Current	0	1	1
Deferred	1	(4)	(5)
Foreign:
Current	335	318	470
Deferred	109	76	0
Total	$ 990	$ 32	$ 412