Stock-based Compensation and Outstanding Awards - Summary of Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2015 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options, Outstanding, Beginning balance	3,545,519
Options, Granted	534,929
Options, Forfeited	(33,261)
Options, Outstanding, Ending balance	4,047,187
Options, Exercisable at September 30, 2015	2,482,499
Weighted average exercise price, Outstanding, Beginning balance | $ / shares	$ 30.86
Weighted average exercise price, Granted | $ / shares	22.44
Weighted average exercise price, Forfeited | $ / shares	29.35
Weighted average exercise price, Outstanding, Ending balance | $ / shares	29.76
Weighted average exercise price, Exercisable at September 30, 2015 | $ / shares	$ 30.92