Stock-Based Compensation - Summary of Outstanding Stock Options and Related Activity (Detail) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding shares, beginning balance	2,170	2,275	2,167
Granted shares	633	120	826
Exercised shares	(4)		(32)
Cancelled shares	(665)	(225)	(686)
Outstanding shares, ending balance	2,134	2,170	2,275
Outstanding weighted average exercise price, beginning balance	$ 6.76	$ 7.02	$ 11.03
Exercisable, shares	1,291	1,573	1,474	2,167
Granted, weighted average exercise price	$ 0.95	$ 1.31	$ 1.39
Vested and expected to vest, shares	1,963
Exercised, weighted average exercise price	$ 1.38		$ 0.50
Cancelled, weighted average exercise price	$ 5.98	$ 6.52	$ 12.37
Outstanding weighted average exercise price, Ending balance	$ 5.29	$ 6.76	$ 7.02
Exercisable, weighted average exercise price	$ 8.04	$ 8.81	$ 10.09	$ 11.03
Vested and expected to vest, weighted average exercise price	$ 5.66
Aggregate intrinsic value	$ 0	$ 0	$ 0	$ 0
Exercisable, Aggregate intrinsic value	0
Vested and expected to vest, Aggregate Intrinsic Value	$ 0