Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2013	$ 106,616	$ 346	$ 101,494	$ 29,776	$ (25,000)
Beginning 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
Shares repurchased under our publicly announced share repurchase programs, Shares		(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
Net income	48,098			48,098
Employee stock purchase and option plans	315	$ 1	314
Employee stock purchase and option plans, Shares		113,996
Shares withheld for taxes on share-based payment awards	(8,086)	$ (1)	(8,085)
Shares withheld for taxes on share-based payment awards, Shares		(115,453)
Stock-based compensation	4,861		4,861
Stock-based compensation, Shares		20,164
Excess tax benefits from stock compensation	3,117		3,117
Shares repurchased under our publicly announced share repurchase programs	(45,227)				$ (45,227)
Shares repurchased under our publicly announced share repurchase programs, Shares					1,134,300
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,134,300)
Ending Balance at Dec. 31, 2015	116,463	$ 348	116,947	119,395	$ (120,227)
Ending Balance, Shares at Dec. 31, 2015		30,904,530			3,914,729
Net income	67,847			67,847
Employee stock purchase and option plans	280	$ 1	279
Employee stock purchase and option plans, Shares		79,175
Shares withheld for taxes on share-based payment awards	(1,933)	$ (1)	(1,932)
Shares withheld for taxes on share-based payment awards, Shares		(13,193)
Stock-based compensation	4,789	$ 1	4,788
Stock-based compensation, Shares		8,992
Shares repurchased under our publicly announced share repurchase programs	(53,285)				$ (53,285)
Shares repurchased under our publicly announced share repurchase programs, Shares					1,578,952
Shares repurchased under our publicly announced share repurchase programs, Shares		(1,578,952)
Ending Balance at Dec. 31, 2016	$ 134,161	$ 349	$ 120,082	$ 187,242	$ (173,512)
Ending Balance, Shares at Dec. 31, 2016		29,400,552			5,493,681