Share-Based Compensation - Summary of Stock Option Activity (Detail)	3 Months Ended
	Mar. 31, 2017 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance of Outstanding, Options | shares	3,086,000
Granted, Options | shares	282,000
Exercised, Options | shares	(16,000)
Cancelled, Options | shares	(16,000)
Ending balance of Outstanding, Options | shares	3,336,000
Exercisable, Options | shares	2,023,000
Beginning balance of Outstanding, Weighted Average Exercise Price | $ / shares	$ 11.18
Granted, Weighted Average Exercise Price | $ / shares	8.30
Exercised, Weighted Average Exercise Price | $ / shares	2.82
Cancelled, Weighted Average Exercise Price | $ / shares	29.68
Ending balance of Outstanding, Weighted Average Exercise Price | $ / shares	10.89
Exercisable, Weighted Average Exercise Price | $ / shares	$ 14.36