Share-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance of Outstanding, Options	2,657,723	3,781,964	3,900,435
Granted, Options	915,122	848,705	746,318
Exercised, Options	(89,773)	(303,035)	(225,000)
Forfeited, Options	(120,964)	(1,278,150)	(299,577)
Cancelled, Options	(276,220)	(391,761)	(340,212)
Ending balance of Outstanding, Options	3,085,888	2,657,723	3,781,964
Exercisable, Options	1,818,745
Beginning balance of Outstanding, Weighted Average Exercise Price	$ 14.27	$ 12.88	$ 15.15
Granted, Weighted Average Exercise Price	4.81	4.83	6.89
Exercised, Weighted Average Exercise Price	4.17	2.73	2.72
Forfeited, Weighted Average Exercise Price	5.11	4.60	4.94
Cancelled, Weighted Average Exercise Price	24.69	20.87	39.49
Ending balance of Outstanding, Weighted Average Exercise Price	11.18	$ 14.27	$ 12.88
Exercisable, Weighted Average Exercise Price	$ 15.63
Outstanding, Weighted Average Remaining Contractual Term	5 years 7 months 28 days
Exercisable, Weighted Average Remaining Contractual Term	3 years 4 months 24 days
Exercised, Aggregate Intrinsic Value	$ 189	$ 620	$ 721
Outstanding, Aggregate Intrinsic Value	10,399
Exercisable, Aggregate Intrinsic Value	$ 3,689