Accumulated Other Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Accumulated Other Comprehensive Income [Abstract]
Net income	$ 45,546	$ 36,130	$ 133,218	$ 103,992
Foreign currency translation adjustment	(7,853)	12,777	(1,485)	7,001
Unrealized loss on interest rate swap, net of tax of $0, $0, $0 and $4, respectively	0	0	0	(7)
Realized loss on interest rate swap reclassed into interest expense, net of tax of $0, $0, $0 and $325, respectively	0	0	0	539
Comprehensive income	37,693	48,907	131,733	111,525
Unrealized loss on interest rate swap, tax	0	0	0	4
Realized loss on interest rate swap reclassed into interest expense, tax	$ 0	$ 0	$ 0	$ 325