Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common stock	Treasury Stock	Additional paid-in capital	Accumulated Other Comprehensive Income	Accumulated deficit
Beginning Balance at Dec. 31, 2009	$ 97,440	$ 21	$ (5,661)	$ 261,974	$ (10)	$ (158,884)
Beginning Balance, Shares at Dec. 31, 2009		21,482,558	(1,249,975)
Exercise of stock options	1,640			1,640
Exercise of stock options, Shares	594,308	532,986
Stock-based compensation	2,252			2,252
Proceeds from secondary public offering net of issuance costs of $4,130	61,651	2		61,649
Proceeds from secondary public offering net of issuance costs of $4,130, Shares		2,195,100
Foreign currency translation adjustments	9				9
Unrealized gain (loss) on investments, net of tax	(9)				(9)
Net income (loss)	29,111					29,111
Ending Balance at Dec. 31, 2010	192,094	23	(5,661)	327,515	(10)	(129,773)
Ending Balance, Shares at Dec. 31, 2010		24,210,644	(1,249,975)
Exercise of stock options	742	1		741
Exercise of stock options, Shares	73,428	71,355
Stock-based compensation	2,297			2,297
Stock issued to Board of Directors	162			162
Stock issued to Board of Directors, Shares		7,724
Purchase of treasury stock, at cost	(6,487)		(6,487)
Purchase of treasury stock, at cost, Shares			(524,869)
Excess tax benefit of stock based compensation	1,404			1,404
Foreign currency translation adjustments	2				2
Unrealized gain (loss) on investments, net of tax	(42)				(42)
Net income (loss)	38,059					38,059
Ending Balance at Dec. 31, 2011	228,231	24	(12,148)	332,119	(50)	(91,714)
Ending Balance, Shares at Dec. 31, 2011		24,289,723	(1,774,844)
Exercise of stock options	73	1		72
Exercise of stock options, Shares	17,885	17,884
Net exercise of stock warrants, Shares		2,188
Stock-based compensation	1,801			1,801
Stock issued to Board of Directors	162			162
Stock issued to Board of Directors, Shares		17,345
Excess tax benefit of stock based compensation	160			160
Foreign currency translation adjustments	(8)				(8)
Unrealized gain (loss) on investments, net of tax	505				505
Net income (loss)	(5,538)					(5,538)
Ending Balance at Dec. 31, 2012	$ 225,386	$ 25	$ (12,148)	$ 334,314	$ 447	$ (97,252)
Ending Balance, Shares at Dec. 31, 2012		24,327,140	(1,774,844)