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 Income And Comprehensive Income [Abstract]
Net income	$ 88,549	$ 73,099	$ 163,658	$ 137,761
Other comprehensive income:
Foreign currency translation gain (loss), net of tax	6,832	(23,422)	22,759	(34,154)
Total other comprehensive income (loss)	6,832	(23,422)	22,759	(34,154)
Total comprehensive income	$ 95,381	$ 49,677	$ 186,417	$ 103,607