Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period (in shares) at Dec. 31, 2017		8,386,000
Balance at beginning of period at Dec. 31, 2017	$ 75,062	$ 8	$ 594,662	$ (520,001)	$ (2,942)	$ 3,335
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		265,000
Exercise of common stock options	705		705
Stock-based compensation expense	2,143		2,143
Issuance of restricted stock (in shares)		88,000
Issuance of restricted stock	0
Restricted stock expense	905		905
Non-employee restricted stock expense	(27)		(27)
Net loss	(19,767)			(19,767)
Other comprehensive loss foreign currency translation	(127)					(127)
Balance at end of period (in shares) at Mar. 31, 2018		8,739,000
Balance at end of period at Mar. 31, 2018	$ 58,894	$ 8	598,388	(539,768)	(2,942)	3,208
Balance at beginning of period (in shares) at Dec. 31, 2018	10,345,367	10,388,000
Balance at beginning of period at Dec. 31, 2018	$ 39,646	$ 10	640,789	(599,715)	(4,026)	2,588
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock purchased	(1)				(1)
Stock-based compensation expense	1,512		1,512
Issuance of restricted stock (in shares)		3,000
Issuance of restricted stock	0
Restricted stock expense	849		849
Net loss	(22,028)			(22,028)
Other comprehensive loss foreign currency translation	$ (598)					(598)
Balance at end of period (in shares) at Mar. 31, 2019	10,347,806	10,391,000
Balance at end of period at Mar. 31, 2019	$ 19,380	$ 10	$ 643,150	$ (621,743)	$ (4,027)	$ 1,990