Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 17,504	$ 18,213	$ 53,170	$ 52,883
Net cumulative translation adjustment and foreign currency exchange hedge, net of tax of $(96), $(242), $(334) and ($215), respectively	(111)	(384)	(492)	(341)
Net unrealized (loss) gain on securities available-for-sale, net of tax of $(16), $11, $16 and $(14), respectively	(27)	18	30	(23)
Less: reclassification adjustment for realized gain from securities available-for-sale included in Other Income, net of tax of $(7), $0, $(19) and $(299), respectively	(12)		(35)	(474)
Net change in unrealized (loss) gain on securities available-for-sale, net of tax	(39)	18	(5)	(497)
Comprehensive Income	$ 17,354	$ 17,847	$ 52,673	$ 52,045