Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares outstanding, beginning balance	217,926	255,906
Number of shares, granted	84,800	59,000
Number of shares, expired	(3,825)	(42,360)
Number of shares, forfeited	(12,189)	(54,620)
Number of shares outstanding, ending balance	286,712	217,926	255,906
Number of shares, exercisable	166,871
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	$ 60.31	$ 75.84
Weighted-average exercise price, granted (usd per share)	2.99	14.41
Weighted-average exercise price, expired (usd per share)	34.07	106.73
Weighted-average exercise price, forfeited (usd per share)	6.26	47.51
Weighted-average exercise price, outstanding (usd per share), ending balance	46.01	$ 60.31	$ 75.84
Weighted-average exercise price, exercisable (usd per share)	$ 73.25
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average remaining contractual term (in years), outstanding	7 years	7 years 3 months	7 years 2 months
Weighted-average remaining contractual term (in years), exercisable	5 years 9 months
Aggregate intrinsic value, outstanding	$ 0	$ 0	$ 0
Aggregate intrinsic value, exercisable	$ 0