CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Net loss attributable to redeemable noncontrolling interest	$ 1	$ 3	$ (23)
Dividends declared per common share (in dollars per share)	$ 1.24	$ 1.16	$ 1.00