Changes in Accumulated Other Comprehensive Income (Loss) Balances (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 04, 2015	Sep. 28, 2014	Oct. 04, 2015	Sep. 28, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 4,689	$ 4,000
Other comprehensive income (loss) before reclassifications, net of tax			(3,593)	2,166
Amounts reclassified from accumulated other comprehensive income, net of tax	$ (321)	$ (712)	(1,029)	(1,307)
Other comprehensive income (loss)	3,229	(850)	(4,622)	859
Ending balance	67	4,859	67	4,859
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			2,365	1,381
Other comprehensive income (loss) before reclassifications, net of tax			(593)	2,166
Amounts reclassified from accumulated other comprehensive income, net of tax			(808)	(1,086)
Other comprehensive income (loss)			(1,401)	1,080
Ending balance	964	2,461	964	2,461
Retirement Plans Prior Service Benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			2,324	2,619
Amounts reclassified from accumulated other comprehensive income, net of tax			(221)	(221)
Other comprehensive income (loss)			(221)	(221)
Ending balance	2,103	$ 2,398	2,103	$ 2,398
Foreign currency translation reclassification adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax			(3,000)
Other comprehensive income (loss)			(3,000)
Ending balance	$ (3,000)		$ (3,000)