Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 53,040	$ 46,514	$ 90,776	$ 83,189
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	876	(1,220)	598	(5,009)
Interest rate hedge – gain	511	814	981	1,375
Pension – actuarial gain	14	1	29	24
Other comprehensive income (loss)	1,401	(405)	1,608	(3,610)
Comprehensive income	$ 54,441	$ 46,109	$ 92,384	$ 79,579