Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Net income (loss) attributable to redeemable noncontrolling interest	$ 4	$ 5	$ 5
Cash dividends declared (USD per share)	$ 3.00	$ 2.54	$ 2.35