Income Taxes (Analysis of the Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ 177	$ 463	$ 523
State	63	52	53
Other countries	229	330	361
Total	469	845	937
United States	16	(68)	(40)
State	22	(3)	31
Other countries	(36)	2	(6)
Total	2	(69)	(15)
Total provision for income taxes	$ 471	$ 776	$ 922