Consolidated Statements of Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings
Balance at Dec. 31, 2013	$ 58,327	$ 266	$ 194,038	$ 0	$ (135,977)
Balance (shares) at Dec. 31, 2013		26,573,023
Increase (Decrease) in Stockholders' Equity
Share-based compensation	8,613		8,613
Exercise of stock options and restricted stock awards	1,861	$ 4	1,857
Exercise of stock options and restricted stock awards (shares)		375,834
Sale of shares under stock purchase plan	466		466
Sale of shares under stock purchase plan (shares)		25,168
Stock issued under ATM	27,572	$ 10	27,562
Stock issued under ATM (shares)		1,017,217
Stock Repurchased During Period	(222)			(222)
Stock Repurchased During Period (shares)		(10,393)
Tax benefit from employee stock plan awards	4,302		4,302
Net (loss) income	96,017				96,017
Balance at Dec. 31, 2014	196,936	$ 280	236,838	(222)	(39,960)
Balance (shares) at Dec. 31, 2014		27,980,849
Increase (Decrease) in Stockholders' Equity
Share-based compensation	15,940		15,940
Exercise of stock options and restricted stock awards	3,355	$ 5	3,350
Exercise of stock options and restricted stock awards (shares)		477,284
Sale of shares under stock purchase plan	851		851
Sale of shares under stock purchase plan (shares)		40,248
Stock issued under ATM	13,534	$ 3	13,531
Stock issued under ATM (shares)		329,402
Stock Repurchased During Period	$ (561)			(561)
Stock Repurchased During Period (shares)		(14,183)
Treasury Stock, Shares, Retired	542
Stock Issued During Period, Value, Treasury Stock Reissued	$ 0			12	(12)
Tax benefit from employee stock plan awards	6,100		6,100
Net (loss) income	(40,381)				(40,381)
Balance at Dec. 31, 2015	195,774	$ 288	276,610	(771)	(80,353)
Balance (shares) at Dec. 31, 2015		28,814,142
Increase (Decrease) in Stockholders' Equity
Share-based compensation	16,707		16,707
Exercise of stock options and restricted stock awards	1,679	$ 4	1,675
Exercise of stock options and restricted stock awards (shares)		296,933
Sale of shares under stock purchase plan	543		543
Sale of shares under stock purchase plan (shares)		58,609
Stock Repurchased During Period	(82)			(82)
Stock Repurchased During Period (shares)		(6,011)
Net (loss) income	(85,155)				(85,155)
Balance at Dec. 31, 2016	$ 129,466	$ 292	$ 295,535	$ (853)	$ (165,508)
Balance (shares) at Dec. 31, 2016		29,163,673