Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2009	$ 317,560	$ 19	$ 211,412	$ 106,466		$ (337)
Beginning balance, Shares at Dec. 31, 2009		19,279,000
Net income	27,171			27,171
Other comprehensive loss	(187)					(187)
Equity compensation	7,533		7,533
Exercise of stock options	966		966
Exercise of stock options, Shares	110,237	110,000
Issuance of shares pursuant to vesting of restricted stock units	1	1
Issuance of shares pursuant to vesting of restricted stock units, Shares		207,000
Net payments for stock issuances and buybacks	(1,225)		66		(1,291)
Net payments for stock issuances and buybacks, Shares		(28,000)			51,000
Tax impact of stock option exercises and award vesting	914		914
Ending balance at Dec. 31, 2010	352,733	20	220,891	133,637	(1,291)	(524)
Ending balance, Shares at Dec. 31, 2010		19,568,000			51,000
Net income	34,865			34,865
Other comprehensive loss	(281)					(281)
Equity compensation	6,658		6,658
Exercise of stock options	478		478
Exercise of stock options, Shares	39,487	39,000
Issuance of shares pursuant to vesting of restricted stock units, Shares		176,000
Net payments for stock issuances and buybacks	(898)		77		(975)
Net payments for stock issuances and buybacks, Shares		9,000			44,000
Tax impact of stock option exercises and award vesting	(527)		(527)
Ending balance at Dec. 31, 2011	393,028	20	227,577	168,502	(2,266)	(805)
Ending balance, Shares at Dec. 31, 2011		19,792,000			95,000
Net income	38,075			38,075
Other comprehensive loss	(436)					(436)
Equity compensation	8,770		8,770
Exercise of stock options	78		78
Exercise of stock options, Shares	11,521	11,000
Issuance of shares pursuant to vesting of restricted stock units, Shares		231,000
Net payments for stock issuances and buybacks	(11,569)		33		(11,602)
Net payments for stock issuances and buybacks, Shares		(475,000)			517,000
Tax impact of stock option exercises and award vesting	804		804
Ending balance at Dec. 31, 2012	$ 428,750	$ 20	$ 237,262	$ 206,577	$ (13,868)	$ (1,241)
Ending balance, Shares at Dec. 31, 2012		19,559,000			612,000