Stock Benefit Plans and Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning balance	4,920
Shares, Granted	4,541
Shares, Exercised	(6)
Shares, Forfeited	(1,645)
Shares Outstanding, Ending balance	7,810	4,920
Shares, Options vested and exercisable	2,640
Shares, Options vested and expected to vest	7,218
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Outstanding, Beginning balance	$ 2.51
Weighted average exercise price, Granted	$ 1.90
Weighted average exercise price, Exercised	$ 1.54
Weighted average exercise price, Forfeited	$ 2.12
Weighted average exercise price, Outstanding, Ending balance	$ 2.23	$ 2.51
Weighted average exercise price, Options vested and exercisable	$ 2.79
Weighted average exercise price, Options vested and expected to vest	$ 2.26
Weighted average remaining contractual term (in years), Outstanding, balance	7 years 7 months 2 days	8 years 0 months 11 days
Options vested and exercisable at December 31, 2013, Weighted average remaining contractual term (in years)	6 years 1 month 6 days
Options vested and expected to vest at December 31, 2013, Weighted average remaining contractual term (in years)	7 years 6 months 4 days
Aggregate intrinsic value, Outstanding, Beginning balance	$ 64
Aggregate intrinsic value, Granted	0
Aggregate intrinsic value, Exercised	0
Aggregate intrinsic value, Forfeited	0
Aggregate intrinsic value, Outstanding, Ending balance	753	64
Aggregate intrinsic value, Options vested and exercisable	125
Aggregate intrinsic value, Options vested and expected to vest	$ 679