Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Stockholders' equity at Dec. 31, 2009	$ 60	$ 559,368	$ (218,798)	$ (13,024)	$ 91,186	$ 418,792
Shares at Dec. 31, 2009	59,771,000		(11,120,000)
Comprehensive income				389	24,057	24,446
Issuance of common stock related to business combinations	1	(5,124)	12,463			7,340
Issuance of common stock related to business combinations, shares			641,000
Other issuances of common stock		3,284	173			3,457
Other issuances of common stock, shares	633,000		10,000
Tax benefits (deficits) on stock options exercised and restricted stock vested		654				654
Vesting of restricted stock, net of forfeitures and tax withholdings		(723)				(723)
Vesting of restricted stock, net of forfeitures and tax withholdings, shares	202,000
Share-based compensation expense		6,755				6,755
Stockholders' equity at Dec. 31, 2010	61	564,214	(206,162)	(12,635)	115,243	460,721
Shares at Dec. 31, 2010	60,606,000		(10,469,000)
Comprehensive income				(146)	41,130	40,984
Issuance of common stock related to business combinations		(5,630)	11,642			6,012
Issuance of common stock related to business combinations, shares			591,000
Other issuances of common stock		1,534	331			1,865
Other issuances of common stock, shares	261,000		17,000
Tax benefits (deficits) on stock options exercised and restricted stock vested		(943)				(943)
Vesting of restricted stock, net of forfeitures and tax withholdings		(340)	(855)			(1,195)
Vesting of restricted stock, net of forfeitures and tax withholdings, shares	365,000		(43,000)
Share-based compensation expense		8,792				8,792
Repurchases of common stock			(2,558)			(2,558)
Repurchases of common stock, shares			(234,000)			234,300
Stockholders' equity at Dec. 31, 2011	61	567,627	(197,602)	(12,781)	156,373	513,678
Shares at Dec. 31, 2011	61,232,000		(10,138,000)
Comprehensive income				4,057	46,169	50,226
Issuance of common stock related to business combinations			2,551			2,551
Issuance of common stock related to business combinations, shares			289,000
Other issuances of common stock	1	3,001	281			3,283
Other issuances of common stock, shares	385,000		14,000			(234,000)
Tax benefits (deficits) on stock options exercised and restricted stock vested		(99)				(99)
Vesting of restricted stock, net of forfeitures and tax withholdings		503	(2,306)			(1,803)
Vesting of restricted stock, net of forfeitures and tax withholdings, shares	458,000		(121,000)
Share-based compensation expense		10,581	(554)			10,027
Additional paid-in capital recorded through compensation-related cost		750				750
Repurchases of common stock			(18,870)			(18,870)
Repurchases of common stock, shares			(1,602,000)			1,601,906
Share-based compensation treasury stock adjustment	29,000		(29,000)
Stockholders' equity at Dec. 31, 2012	$ 62	$ 582,363	$ (216,500)	$ (8,724)	$ 202,542	$ 559,743
Shares at Dec. 31, 2012	62,104,000		(11,587,000)