Income Taxes (Domestic and Foreign Components of Income Before Income Tax Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ 636	$ 556	$ (153)
Foreign	428	316	286
Income before income taxes	$ 1,064	$ 872	$ 133