Consolidated Statement of Stockholders' Equity (Deficit) - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit
Balance at December 31, 2015 at Dec. 31, 2015	$ 195,774	$ 288	$ 276,610	$ (771)	$ (80,353)
Balance (shares) at December 31, 2015 at Dec. 31, 2015	28,814,142
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	$ 9,244		9,244
Exercise of stock options and restricted stock vested	$ 212	2	210
Exercise of stock options and restricted stock vested (shares)	111,459
Sale of shares under stock purchase plan	$ 363		363
Sale of shares under stock purchase plan (shares)	37,888
Shares withheld for statutory tax withholding	$ (13)			(13)
Shares withheld for statutory tax withholding (shares)	(1,193)
Tax shortfall from employee stock plan awards	$ (127)		(127)
Net loss	(56,109)				(56,109)
Balance at June 30, 2016 at Jun. 30, 2016	$ 149,344	$ 290	$ 286,300	$ (784)	$ (136,462)
Balance at June 30, 2016 (shares) at Jun. 30, 2016	28,962,296