Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 97,330	$ 81,972	$ 71,993
Other comprehensive income (loss), net of tax [Abstract]
Foreign currency translation adjustments	2,013	(534)	(609)
Change in unrealized gains and losses on interest rate swaps, net of tax	1,033	(1,820)	1,777
Total other comprehensive income (loss)	3,046	(2,354)	1,168
Comprehensive Income	$ 100,376	$ 79,618	$ 73,161