Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2008	$ 48	$ 0	$ 189,665	$ 54,407	$ (2,386)	$ 241,734
Balance (in shares) at Dec. 31, 2008	48,218,872
Net income	0	0	0	19,202	0	19,202
Foreign currency translation	0	0	0	0	2,434	2,434
Interest rate swaps, net of tax	0	0	0	0	2,178	2,178
Comprehensive income, net of tax						23,814
Treasury stock (in shares)	0					48,970
Treasury stock, value of common stock	0	(1,171)	0	0	0	(1,171)
Retirement of treasury shares (in shares)	(48,970)					(48,970)
Retirement of treasury shares	0	1,171	0	(1,171)	0	0
Share-based compensation	0	0	6,429	0	0	6,429
Exercise and lapse of share-based awards, including tax benefit (in shares)	557,252
Exercise and lapse of share-based awards, including tax benefit	1	0	5,846	0	0	5,847
Declaration of cash dividends	0	0	0	(25,310)	0	(25,310)
Issuance of restricted stock, net (in shares)	206,492
Issuance of restricted stock, net	0	0	0	0	0	0
Employee stock purchase plan (in shares)	58,083
Employee stock purchase plan	0	0	844	0	0	844
Balance at Dec. 31, 2009	49	0	202,784	47,128	2,226	252,187
Balance (in shares) at Dec. 31, 2009	48,991,729
Net income	0	0	0	57,638	0	57,638
Foreign currency translation	0	0	0	0	(2,170)	(2,170)
Interest rate swaps, net of tax	0	0	0	0	996	996
Comprehensive income, net of tax						56,464
Treasury stock (in shares)	(637,710)					637,710
Treasury stock, value of common stock	0	(13,683)	0	0	0	(13,683)
Retirement of treasury shares (in shares)	0					(534,610)
Retirement of treasury shares	0	11,339	0	(11,339)	0	0
Share-based compensation	0	0	7,790	0	0	7,790
Exercise and lapse of share-based awards, including tax benefit (in shares)	650,210
Exercise and lapse of share-based awards, including tax benefit	0	0	7,287	0	0	7,287
Declaration of cash dividends	0	0	0	(25,746)	0	(25,746)
Issuance of restricted stock, net (in shares)	220,206
Issuance of restricted stock, net	0	0	0	0	0	0
Employee stock purchase plan (in shares)	54,143
Employee stock purchase plan	0	0	883	0	0	883
Balance at Dec. 31, 2010	49	(2,344)	218,744	67,681	1,052	285,182
Balance (in shares) at Dec. 31, 2010	49,278,578					49,278,578
Net income	0	0	0	71,993	0	71,993
Foreign currency translation	0	0	0	0	(609)	(609)
Interest rate swaps, net of tax	0	0	0	0	1,777	1,777
Comprehensive income, net of tax						73,161
Treasury stock (in shares)	(3,033,733)					3,033,733
Treasury stock, value of common stock	0	(76,564)	0	0	0	(76,564)
Retirement of treasury shares (in shares)	0					(3,136,833)
Retirement of treasury shares	(3)	78,908	0	(78,905)	0	0
Share-based compensation	0	0	8,233	0	0	8,233
Exercise and lapse of share-based awards, including tax benefit (in shares)	958,509
Exercise and lapse of share-based awards, including tax benefit	1	0	15,292	0	0	15,293
Declaration of cash dividends	0	0	0	(26,470)	0	(26,470)
Issuance of restricted stock, net (in shares)	119,525
Issuance of restricted stock, net	0	0	0	0	0	0
Employee stock purchase plan (in shares)	44,118
Employee stock purchase plan	0	0	911	0	0	911
Balance at Dec. 31, 2011	$ 47	$ 0	$ 243,180	$ 34,299	$ 2,220	$ 279,746
Balance (in shares) at Dec. 31, 2011	47,366,997					47,366,997