CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Beginning Balance (in shares) at Dec. 31, 2014		37,366,098
Beginning Balance at Dec. 31, 2014	$ 258,454	$ 37	$ 386,795	$ (130,205)	$ 1,827	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(39,216)			(39,216)
Other comprehensive income (loss)	62				62
Stock-based compensation	11,188		11,188
Issuances of common stock pursuant to securities purchase and other agreements (in shares)		2,907,490
Issuances of common stock pursuant to securities purchase and other agreements	54,157	$ 3	54,154
Issuance and exercise of stock-based compensation benefit plans, net of income tax (in shares)		1,064,104
Issuance and exercise of stock-based compensation benefit plans, net of income tax	2,017	$ 1	2,016
Ending Balance (in shares) at Dec. 31, 2015		41,337,692
Ending Balance at Dec. 31, 2015	286,662	$ 41	454,153	(169,421)	1,889	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(41,660)			(41,660)
Other comprehensive income (loss)	(3,660)				(3,660)
Stock-based compensation	6,956		6,956
Convertible senior notes equity conversion option	11,666		11,666
Debt issuance costs allocated to equity and other	(640)		(640)
Issuance and exercise of stock-based compensation benefit plans, net of income tax (in shares)		953,660				8,611
Issuance and exercise of stock-based compensation benefit plans, net of income tax	$ 2,244	$ 1	2,377			$ (134)
Ending Balance (in shares) at Dec. 31, 2016	42,282,741	42,291,352				8,611
Ending Balance at Dec. 31, 2016	$ 261,568	$ 42	474,512	(211,081)	(1,771)	$ (134)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(37,145)			(37,145)
Other comprehensive income (loss)	2,647				2,647
Stock-based compensation	$ 5,932		5,932
Issuance and exercise of stock-based compensation benefit plans, net of income tax (in shares)	842,704	1,098,224				7,354
Issuance and exercise of stock-based compensation benefit plans, net of income tax	$ 9,397	$ 1	9,573			$ (177)
Ending Balance (in shares) at Dec. 31, 2017	43,373,611	43,389,576				15,965
Ending Balance at Dec. 31, 2017	$ 242,399	$ 43	$ 491,012	$ (249,221)	$ 876	$ (311)