Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2016	Jul. 05, 2015	Jul. 03, 2016	Jul. 05, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 26	$ 82	$ 61	$ 294
Unrealized Gains (Losses) on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	13	40	2	209
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	(47)	(42)	(93)	(85)
Accumulated Defined Benefit Plans Adjustment, Net Prior Services Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 34	$ 0	$ 34	$ 0