Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares outstanding, beginning balance	2,086,450	2,068,720	562,025
Number of shares, granted	1,352,114	348,000	1,532,000
Number of shares, exercised	(56,250)	0	0
Number of shares, expired	(65,250)	(51,637)
Number of shares, forfeited	(182,970)	(278,633)	(25,305)
Number of shares outstanding, ending balance	3,134,094	2,086,450	2,068,720	562,025
Number of shares, vested and expected to vest	3,015,584
Number of shares, exercisable	1,479,939
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-average exercise price, outstanding (usd per share), beginning balance	$ 7.43	$ 7.93	$ 18.56
Weighted-average exercise price, granted (usd per share)	4.48	4.19	4.15
Weighted-average exercise price, exercised (usd per share)	4.53
Weighted-average exercise price, expired (usd per share)	10.54	21.61
Weighted-average exercise price, forfeited (usd per share)	5.91	4.45	14.71
Weighted-average exercise price, outstanding (usd per share), ending balance	6.23	$ 7.43	$ 7.93	$ 18.56
Weighted-average exercise price, vested and expected to vest (usd per share)	6.32
Weighted-average exercise price, exercisable (usd per share)	$ 8.47
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average remaining contractual term (in years), outstanding	8 years	7 years 2 months	8 years 5 months	7 years
Weighted-average remaining contractual term (in years), vested and expected to vest	7 years 11 months
Weighted-average remaining contractual term (in years), exercisable	7 years 1 month
Aggregate intrinsic value, outstanding	$ 1,630	$ 0	$ 544	$ 0
Aggregate intrinsic value, vested and expected to vest	1,556
Aggregate intrinsic value, exercisable	$ 624