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, 2014		67,322,000
Stockholders' equity, Balance at beginning 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 (in shares)		0
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		68,235,000
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	(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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		129,000
Exercise of common stock options	546	$ 0	546
Employee stock purchase plan (in shares)		446,000
Employee stock purchase plan	2,519		2,518
Stock compensation expense	8,538		8,538
Issuance of restricted stock (in shares)		294,000
Issuance of restricted stock	0
Restricted stock expense	3,027		3,027
Non-employee restricted stock expense	79		79
Equity conversion option	(2,235)		(2,235)
Deerfield warrants	14,704		14,704
Debt issuance costs allocated to equity	(356)		(356)
Net loss	(66,400)			(66,400)
Other comprehensive loss	$ 1,847					1,847
Common Stock, Balance at end of period (in shares) at Dec. 31, 2017	83,643,585	83,855,000
Stockholders' equity, Balance at end of period at Dec. 31, 2017	$ 75,062	$ 84	$ 594,586	$ (520,001)	$ (2,942)	$ 3,335