Share-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance of Outstanding, Options	3,781,964	3,900,435	2,591,887
Granted, Options	848,705	746,318	1,934,005
Exercised, Options	(303,035)	(225,000)	(1,275)
Forfeited, Options	(1,278,150)	(299,577)	(261,366)
Cancelled, Options	(391,761)	(340,212)	(362,816)
Ending balance of Outstanding, Options	2,657,723	3,781,964	3,900,435
Exercisable, Options	1,819,466
Beginning balance of Outstanding, Weighted Average Exercise Price	$ 12.88	$ 15.15	$ 25.96
Granted, Weighted Average Exercise Price	4.83	6.89	2.58
Exercised, Weighted Average Exercise Price	2.73	2.72	3.08
Forfeited, Weighted Average Exercise Price	4.60	4.94	5.19
Cancelled, Weighted Average Exercise Price	20.87	39.49	31.60
Ending balance of Outstanding, Weighted Average Exercise Price	14.27	$ 12.88	$ 15.15
Exercisable, Weighted Average Exercise Price	$ 18.71
Outstanding, Weighted Average Remaining Contractual Term	4 years 11 months 9 days
Exercisable, Weighted Average Remaining Contractual Term	3 years 1 month 6 days
Exercised, Aggregate Intrinsic Value	$ 620	$ 721	$ 3
Outstanding, Aggregate Intrinsic Value	254
Exercisable, Aggregate Intrinsic Value	$ 154