Stock Benefit Plans and Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning balance	8,267
Shares, Granted	457
Shares, Exercised	(5)
Shares, Forfeited	(1,081)
Shares Outstanding, Ending balance		8,267
Shares, Options vested and exercisable	5,170
Shares, Options vested and expected to vest	7,304
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Outstanding, Beginning balance	$ 2.08
Weighted average exercise price, Granted	1.28
Weighted average exercise price, Exercised	0.00
Weighted average exercise price, Forfeited	2.10
Weighted average exercise price, Outstanding, Ending balance	2.03	$ 2.08
Weighted average exercise price, Options vested and exercisable	2.25
Weighted average exercise price, Options vested and expected to vest	$ 2.05
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term, Outstanding, balance	6 years 4 months 10 days	7 years 4 months 6 days
Options vested and exercisable at December 31, 2014, Weighted average remaining contractual term (in years)	5 years 7 months 18 days
Options vested and expected to vest at December 31, 2014, Weighted average remaining contractual term (in years)	6 years 3 months 1 day
Aggregate intrinsic value, Outstanding, Beginning balance	$ 71
Aggregate intrinsic value, Granted	0
Aggregate intrinsic value, Exercised	0
Aggregate intrinsic value, Forfeited	0
Aggregate intrinsic value, Outstanding, Ending balance	0	$ 71
Aggregate intrinsic value, Options vested and exercisable	0
Aggregate intrinsic value, Options vested and expected to vest	$ 0
Common stock reserved for future issuance	26,125