CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2008	$ 63,583	$ 47	$ 180,869	$ (117,195)	$ (138)
Beginning Balance (in shares) at Dec. 31, 2008		47,357,017
Repurchase of common stock (in shares)		(16,223)
Repurchase of common stock	(28)		(28)
Common stock issued upon exercise of stock options (in shares)		2,094,888
Common stock issued upon exercise of stock options	4,191	2	4,189
Stock-based compensation	4,726		4,726
Tax benefit from exercise of employee stock options	936		936
Net income	7,763			7,763
Other comprehensive loss	(34)				(34)
Ending Balance at Dec. 31, 2009	81,137	49	190,692	(109,432)	(172)
Ending Balance (in shares) at Dec. 31, 2009		49,435,682
Repurchase of common stock (in shares)		(534,496)
Repurchase of common stock	(3,649)		(3,649)
Common stock issued upon exercise of stock options (in shares)		2,843,547
Common stock issued upon exercise of stock options	11,410	3	11,407
Stock-based compensation	5,142		5,142
Common stock issued under Employee Stock Purchase Plan (in shares)		9,109
Common stock issued under Employee Stock Purchase Plan	74		74
Tax benefit from exercise of employee stock options	1,397		1,397
Net income	9,259			9,259
Other comprehensive loss	(127)				(127)
Ending Balance at Dec. 31, 2010	104,643	52	205,063	(100,173)	(299)
Ending Balance (in shares) at Dec. 31, 2010		51,753,842
Common stock issued upon exercise of stock options (in shares)		2,278,451
Common stock issued upon exercise of stock options	9,708	2	9,706
Stock-based compensation	6,771		6,771
Common stock issued under Employee Stock Purchase Plan (in shares)		58,051
Common stock issued under Employee Stock Purchase Plan	572		572
Tax benefit from exercise of employee stock options	4,001		4,001
Net income	12,038			12,038
Other comprehensive loss	(35)				(35)
Ending Balance at Dec. 31, 2011	$ 137,698	$ 54	$ 226,113	$ (88,135)	$ (334)
Ending Balance (in shares) at Dec. 31, 2011		54,090,344