CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2017	$ 44,753	$ 554	$ 106,312	$ (60,094)	$ (2,019)
Balance (in shares) at Dec. 31, 2017		53,400,281
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock to consultant	102		102
Issuance of stock to consultant (in shares)		25,000
Stock based compensation expense	2,066		2,066
Stock options exercised	251	$ 2	249
Stock options exercised (in shares)		239,000
Issuance of stock for vested restricted stock units	0	$ 1	(1)
Issuance of stock for vested restricted stock units (in shares)		109,940
Fair value of conversion feature on Convertible 4.75% Senior Notes	18,658		18,658
Partial extinguishment of equity component of Convertible 3.75% Senior Notes	(10,522)		(10,522)
Cumulative translation adjustment	(631)				(631)
Net loss	(36,256)			(36,256)
Balance at Dec. 31, 2018	18,421	$ 557	116,864	(96,350)	(2,650)
Balance (in shares) at Dec. 31, 2018		53,774,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation expense	1,104		1,104
Issuance of stock for vested restricted stock units	0	$ 1	(1)
Issuance of stock for vested restricted stock units (in shares)		76,206
Cumulative translation adjustment	292				292
Net loss	(25,124)
Balance at Dec. 31, 2019	$ (5,307)	$ 558	$ 117,967	$ (121,474)	$ (2,358)
Balance (in shares) at Dec. 31, 2019		53,850,427