Unaudited Condensed Consolidated Statements of Shareholders Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2017		18,701,935
Beginning balance at Dec. 31, 2017	$ 14,938	$ 551,925	$ 73,185	$ (713,974)	$ 103,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(32,828)			(32,828)
Foreign currency translation adjustment	655				655
Stock-based compensation expense	906		906
Vesting of restricted stock, net of shares withheld for taxes (in shares)		1,276
Vesting of restricted stock, net of shares withheld for taxes	(3)		(3)
Fair value allocated to warrants	3,277		3,277
Ending balance (in shares) at Mar. 31, 2018		18,703,211
Ending balance at Mar. 31, 2018	(13,055)	$ 551,925	77,365	(746,802)	104,457
Beginning balance (in shares) at Dec. 31, 2017		18,701,935
Beginning balance at Dec. 31, 2017	14,938	$ 551,925	73,185	(713,974)	103,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(88,898)
Foreign currency translation adjustment	(1,375)
Ending balance (in shares) at Sep. 30, 2018		18,854,971
Ending balance at Sep. 30, 2018	(69,188)	$ 552,506	78,751	(802,872)	102,427
Beginning balance (in shares) at Mar. 31, 2018		18,703,211
Beginning balance at Mar. 31, 2018	(13,055)	$ 551,925	77,365	(746,802)	104,457
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(31,262)			(31,262)
Foreign currency translation adjustment	(1,995)				(1,995)
Stock-based compensation expense	937		937
Vesting of restricted stock, net of shares withheld for taxes (in shares)		17,036
Vesting of restricted stock, net of shares withheld for taxes	(25)		(25)
Issuance of common stock under employee stock purchase plan (in shares)		132,066
Issuance of common stock under employee stock purchase plan	440	$ 581	(141)
Ending balance (in shares) at Jun. 30, 2018		18,852,313
Ending balance at Jun. 30, 2018	(44,960)	$ 552,506	78,136	(778,064)	102,462
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(24,808)			(24,808)
Foreign currency translation adjustment	(35)				(35)
Stock-based compensation expense	618		618
Vesting of restricted stock, net of shares withheld for taxes (in shares)		2,658
Vesting of restricted stock, net of shares withheld for taxes	(3)		(3)
Ending balance (in shares) at Sep. 30, 2018		18,854,971
Ending balance at Sep. 30, 2018	$ (69,188)	$ 552,506	$ 78,751	$ (802,872)	$ 102,427