Stock-based Compensation and Outstanding Awards - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options, Outstanding, Beginning balance | shares	3,990
Stock Options, Granted | shares	978
Stock Options, Forfeited | shares	(95)
Stock Options, Exercised or settled | shares	(20)
Stock Options, Outstanding, Ending balance | shares	4,853
Stock Options, Exercisable at December 31, 2016 | shares	3,225
Weighted average exercise price, Outstanding, Beginning balance | $ / shares	$ 29.81
Weighted average exercise price, Granted | $ / shares	14.02
Weighted average exercise price, Forfeited | $ / shares	22.75
Weighted average exercise price, Exercised or settled | $ / shares	14.06
Weighted average exercise price, Outstanding, Ending balance | $ / shares	26.83
Weighted average exercise price, Exercisable at December 31, 2016 | $ / shares	$ 30.58
Weighted average remaining contractual term, Outstanding, Ending balance	5 years 8 months 12 days
Weighted average remaining contractual term, Exercisable at December 31, 2016	5 years 6 months
Aggregate intrinsic value, Outstanding, Ending balance | $	$ 7
Aggregate intrinsic value, Exercisable at December 31, 2016 | $	$ 1