Income Taxes (Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
United States	$ 20	$ 71	$ 14
Other nations	31	30	67
States (U.S.)	18	13	11
Current income tax expense	69	114	92
United States	180	154	(503)
Other nations	36	(13)	(11)
States (U.S.)	(3)	19	(43)
Deferred income tax expense (benefit)	213	160	(557)
Total income tax expense (benefit)	$ 282	$ 274	$ (465)