Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 73,573,000	$ 68,098,000	$ 69,869,000
Other comprehensive loss, net of tax:
Net unrealized gain on cash flow hedges, net of tax of $13	104,000	0
Net unrealized gain (loss) on available-for-sale investments, net of tax of ($147), $129, and $123 in 2013, 2012, and 2011, respectively	(190,000)	2,079,000	174,000
Foreign currency translation adjustments, net of tax of $22, $7, and $238 in 2013, 2012, and 2011, respectively	82,000	(12,546,000)	(8,491,000)
Other comprehensive loss	(4,000)	(10,467,000)	(8,317,000)
Comprehensive income	$ 73,569,000	$ 57,631,000	$ 61,552,000