Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 155,173	$ 140,826	$ 344,679	$ 318,632
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax benefit (expense) of $313 and $526 in 2015 and $91 and ($48) in 2014	(5,072)	(22,424)	(32,763)	(22,576)
Unrealized gain (loss) on derivative instruments, net of tax expense of $1,982 and $2,119 in 2015 and $1,549 and $945 in 2014	3,332	2,603	3,563	1,588
Comprehensive income	$ 153,433	$ 121,005	$ 315,479	$ 297,644