Condensed Consolidated Statements of Stockholders' Equity and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data	Total	Comprehensive Income Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income
Beginning Balance, Value at Dec. 31, 2010	$ 231,268		$ 3,602	$ (76)	$ 153,221	$ 67,642	$ 6,879
Beginning Balance, Issued Shares at Dec. 31, 2010	36,057,791		36,057,791
Beginning Balance, Treasury Shares at Dec. 31, 2010				40,509
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	54,048	54,048				54,048
Cumulative translation adjustment	(6,441)	(6,441)					(6,441)
Comprehensive income		47,607
Repurchase and retirement of common stock, Shares			(3,322,973)
Repurchase and retirement of common stock, Value	(61,002)		(332)		(60,670)
Vesting of restricted stock, Shares			127,735
Vesting of restricted stock, Value			12		(12)
Stock Issued During Period, Value, Conversion of Convertible Securities	(1,850)				(1,850)
Exercise of stock options, Shares			21,509
Stock Issued During Period, Value, Stock Options Exercised			2
Exercise of stock options, Value	14				12
Deferred compensation and amortization related to options and restricted stock	1,737				1,737
Share subscribed for business acquisition, Shares			3,650,914
Share subscribed for business acquisition, Value	87,476		365		87,111
Tax benefit related to share-based compensation	70				70
Ending Balance, Value at Sep. 30, 2011	$ 305,320		$ 3,649	$ (76)	$ 179,619	$ 121,690	$ 438
Ending Balance, Issued Shares at Sep. 30, 2011	36,534,976		36,534,976
Ending Balance, Treasury Shares at Sep. 30, 2011				40,509