Earnings per Share - Reconciliation of Numerators and Denominators of the Earnings per Share Calculations (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income attributable to the parent company	$ 100	$ 95	$ 124	$ 108	$ (104)	$ 69	$ 71	$ 75	$ 427	$ 111	$ 640
Less: Redeemable noncontrolling interests adjustment to redemption value										(6)
Net income available to common stockholders - Numerator diluted									427	105	640
Net income available to common stockholders - Numerator basic									$ 427	$ 105	$ 640
Weighted-average common shares outstanding - Basic									145.0	145.1	146.0
Employee compensation-related shares, including stock options									1.5	1.8	0.8
Weighted-average common shares outstanding - Diluted									146.5	146.9	146.8