Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 28, 2014		Sep. 29, 2013		Sep. 28, 2014		Sep. 29, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains	$ 638		$ 189		$ 1,086		$ 401
Prior service benefit	74	[1]	69	[1]	221	[1]	207	[1]
Total reclassifications	$ 712		$ 258		$ 1,307		$ 608

[1] The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: "Retirement Plans."