Description of Business, Basis of Presentation and Significant Accounting Policies - Components of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Description of Business, Basis of Presentation and Significant Accounting Policies [Abstract]
Net income (loss) attributable to common stockholders	$ 58	$ 49	$ 64	$ (46)	$ (49)	$ 78	$ (265)	$ 22	$ 125	$ (214)	$ 367
Weighted average outstanding shares of common stock									129.7	139.6	155.3
Dilutive effect of employee stock options, restricted shares and other stock awards									1.8	0.0	2.5
Common stock and common stock equivalents									131.5	139.6	157.8
Net (loss) income per share:
Basic (in usd per share)	$ 0.45	$ 0.38	$ 0.49	$ (0.36)	$ (0.37)	$ 0.56	$ (1.87)	$ 0.15	$ 0.96	$ (1.53)	$ 2.36
Diluted (in usd per share)	$ 0.44	$ 0.37	$ 0.49	$ (0.36)	$ (0.37)	$ 0.55	$ (1.87)	$ 0.15	$ 0.95	$ (1.53)	$ 2.33