Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Common Stock, Balance at beginning of period (in shares) at Dec. 31, 2013		63,866,000
Stockholders' Equity, Balance at beginning of period at Dec. 31, 2013	$ 104,641	$ 64	$ 321,756	$ (216,082)	$ 0	$ (1,097)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		315,000
Exercise of common stock options	1,776		1,776
Employee stock purchase plan (in shares)		254,000
Employee stock purchase plan	2,613		2,613
Issuance of common stock (in shares)		2,684,000
Issuance of common stock	38,630	$ 3	38,627
Treasury stock purchased (in shares)		58,000
Treasury stock purchased	(2,328)				(2,328)
Stock compensation expense	5,172		5,172
Issuance of restricted stock (in shares)		145,000
Issuance of restricted stock	0
Restricted stock expense	2,620		2,620
Non-employee restricted stock expense	75		75
Net loss	(32,418)			(32,418)
Other comprehensive loss	3,369					3,369
Common Stock, Balance at end of period (in shares) at Dec. 31, 2014		67,322,000
Stockholders' Equity, Balance at end of period at Dec. 31, 2014	124,150	$ 67	372,639	(248,500)	(2,328)	2,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		397,000
Exercise of common stock options	2,871	$ 1	2,870
Employee stock purchase plan (in shares)		355,000
Employee stock purchase plan	2,962		2,962
Treasury stock purchased	(481)				(481)
Stock compensation expense	6,266		6,266
Issuance of restricted stock (in shares)		161,000
Issuance of restricted stock	0
Restricted stock expense	2,843		2,843
Non-employee restricted stock expense	146		146
Equity conversion option	17,547		17,547
Debt issuance costs allocated to equity	(811)		(811)
Net loss	(50,424)			(50,424)
Other comprehensive loss	$ (1,762)					(1,762)
Common Stock, Balance at end of period (in shares) at Dec. 31, 2015	68,034,386	68,235,000
Stockholders' Equity, Balance at end of period at Dec. 31, 2015	$ 103,307	$ 68	404,462	(298,924)	(2,809)	510
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		524,000
Exercise of common stock options	3,129	$ 2	3,127
Employee stock purchase plan (in shares)		394,000
Employee stock purchase plan	3,216		3,216
Issuance of common stock (in shares)		13,587,000
Issuance of common stock	100,812	$ 13	100,799
Treasury stock purchased (in shares)		11,000
Treasury stock purchased	(133)				(133)
Stock compensation expense	8,541		8,541
Issuance of restricted stock (in shares)		235,000
Issuance of restricted stock	0
Restricted stock expense	3,715		3,715
Non-employee restricted stock expense	30		30
Equity conversion option	43,875		43,875
Net loss	(154,677)			(154,677)
Other comprehensive loss	$ 978					978
Common Stock, Balance at end of period (in shares) at Dec. 31, 2016	82,774,005	82,986,000
Stockholders' Equity, Balance at end of period at Dec. 31, 2016	$ 112,793	$ 83	$ 567,765	$ (453,601)	$ (2,942)	$ 1,488