Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional paid-in Capital [Member]	Accum Other Comp Inc. [Member]	Accum deficit [Member]
Beginning Balance at Dec. 31, 2012	$ 225,386	$ 25	$ (12,148)	$ 334,314	$ 447	$ (97,252)
Beginning Balance, Shares at Dec. 31, 2012		24,327,140
Beginning Balance, Treasury Shares at Dec. 31, 2012			(1,774,844)
Exercise of stock options	$ 140			140
Exercise of stock options, Shares	27,930	27,930
Stock-based compensation	$ 1,246			1,246
Restricted stock issued	292			292
Restricted stock issued, shares		73,707
Excess tax benefit of stock based compensation	(114)			(114)
Stock issued to Board of Directors	57			57
Stock issued to Board of Directors, Shares		4,746
Foreign currency translation adjustments	(2)				(2)
Unrealized (gain) loss on investments, net of tax	(863)				(863)
Net loss	(30,351)					(30,351)
Ending Balance at Dec. 31, 2013	195,791	$ 25	$ (12,148)	335,935	(418)	(127,603)
Ending Balance, Shares at Dec. 31, 2013		24,433,523
Ending Balance, Treasury Shares at Dec. 31, 2013			(1,774,844)
Exercise of stock options	$ 256			256
Exercise of stock options, Shares	47,654	47,654
Stock-based compensation	$ 960			960
Restricted stock issued, net of unvested restricted stock cancelled	448			448
Restricted stock issued, net of unvested restricted stock cancelled, Shares		7,013
Common stock issued, net of shares withheld for employee taxes	(55)			(55)
Common stock issued, net of shares withheld for employee taxes, Shares		3,098
Common stock issued, net of issuance costs	34,778	$ 3		34,775
Common stock issued, net of issuance costs, Shares		3,422,500
Reclassification of unrealized gain included in net loss	388				388
Foreign currency translation adjustments	(4)				(4)
Unrealized (gain) loss on investments, net of tax	(9)				(9)
Net loss	(43,993)					(43,993)
Ending Balance at Dec. 31, 2014	$ 188,560	$ 28	$ (12,148)	372,319	(43)	(171,596)
Ending Balance, Shares at Dec. 31, 2014		27,913,788
Ending Balance, Treasury Shares at Dec. 31, 2014	(1,774,844)		(1,774,844)
Exercise of stock options	$ 4			4
Exercise of stock options, Shares	5,692	5,692
Stock-based compensation	$ 731			731
Restricted stock issued, net of restricted shares withheld for employee taxes	287			287
Restricted stock issued, net of restricted shares withheld for employee taxes, Shares		58,899
Common stock issued, net of shares withheld for employee taxes	224			224
Common stock issued, net of shares withheld for employee taxes, Shares		29,432
Unrealized (gain) loss on investments, net of tax	10				10
Net loss	(77,830)					(77,830)
Ending Balance at Dec. 31, 2015	$ 111,986	$ 28	$ (12,148)	$ 373,565	$ (33)	$ (249,426)
Ending Balance, Shares at Dec. 31, 2015		28,007,811
Ending Balance, Treasury Shares at Dec. 31, 2015	(1,774,844)		(1,774,844)