Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 20,727	$ 17,805	$ 53,130	$ 51,854
Other comprehensive income (loss), net of tax:
Net unrealized gain (loss) on available-for-sale investments, net of tax of $152 and $102 in the three-month periods and net of tax of ($124) and $302 in the nine-month periods, respectively	764	523	(342)	2,141
Foreign currency translation adjustments, net of tax of $302 and $17 in the three-month periods and net of tax of $121 and ($180) in the nine-month periods, respectively	1,626	(2,905)	(181)	(12,086)
Other comprehensive income (loss)	2,390	(2,382)	(523)	(9,945)
Total comprehensive income	$ 23,117	$ 15,423	$ 52,607	$ 41,909