Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2011	$ 92,499	$ 329	$ 99,712	$ (7,542)
Beginning Balance, Shares at Dec. 31, 2011		31,204,264
Net income	2,720			2,720
Employee stock purchase and option plans	822	2	820
Employee stock purchase and option plans, Shares		469,104
Shares withheld for taxes on share-based payment awards	(5,524)	1	(5,525)
Shares withheld for taxes on share-based payment awards, Shares		(74,302)
Stock-based compensation	3,469		3,469
Stock-based compensation, Shares		298,430
Common stock issued upon conversion of notes		11	(11)
Common stock issued upon conversion of notes, Shares		2,123,490
Ending Balance at Dec. 31, 2012	93,986	343	98,465	(4,822)
Ending Balance, Shares at Dec. 31, 2012		34,020,986
Net income	34,598			34,598
Employee stock purchase and option plans	4,032	3	4,029
Employee stock purchase and option plans, Shares		542,670
Shares withheld for taxes on share-based payment awards	(6,277)		(6,277)
Shares withheld for taxes on share-based payment awards, Shares		(58,730)
Stock-based compensation	3,811		3,811
Stock-based compensation, Shares		93,198
Excess tax benefits from stock compensation	1,466		1,466
Shares repurchased under our publicly announced share repurchase programs	(25,000)				(25,000)
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,122,510)			1,122,510
Ending Balance at Dec. 31, 2013	106,616	346	101,494	29,776	(25,000)
Ending Balance, Shares at Dec. 31, 2013		33,475,614			1,122,510
Net income	41,521			41,521
Employee stock purchase and option plans	747	1	746
Employee stock purchase and option plans, Shares		133,133
Shares withheld for taxes on share-based payment awards	(3,189)		(3,189)
Shares withheld for taxes on share-based payment awards, Shares		(36,610)
Stock-based compensation	4,807	1	4,806
Stock-based compensation, Shares		105,905
Excess tax benefits from stock compensation	12,883		12,883
Shares repurchased under our publicly announced share repurchase programs	(50,000)				(50,000)
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,657,919)			1,657,919
Ending Balance at Dec. 31, 2014	$ 113,385	$ 348	$ 116,740	$ 71,297	$ (75,000)
Ending Balance, Shares at Dec. 31, 2014		32,020,123			2,780,429