Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 16,820	$ 19,767	$ 32,403	$ 34,049
Other comprehensive loss, net of tax:
Net unrealized gain (loss) on available-for-sale investments, net of tax of ($318) and ($91) in the three-month periods and net of tax of ($276) and $200 in the six-month periods, respectively	(1,279)	304	(1,106)	1,618
Foreign currency translation adjustments, net of tax of $46 and ($403) in the three-month periods and net of tax of ($181) and ($197) in the six-month periods, respectively	687	(14,507)	(1,807)	(9,181)
Other comprehensive loss	(592)	(14,203)	(2,913)	(7,563)
Comprehensive income	$ 16,228	$ 5,564	$ 29,490	$ 26,486