Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 80,004	$ 69,823	$ 155,468	$ 129,901
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net of tax benefit of $169 and $221 in 2013 and $295 and $130 in 2012	(4,688)	(5,734)	(6,327)	(2,070)
Unrealized gain (loss) on derivative instruments, net of tax (expense) benefit of ($1,137) and ($1,796) in 2013 and ($778) and $1,070 in 2012	1,913	1,775	3,020	(1,646)
Comprehensive income	$ 77,229	$ 65,864	$ 152,161	$ 126,185