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. 29, 2013		Sep. 30, 2012		Sep. 29, 2013		Sep. 30, 2012
Other Comprehensive Income (Loss) [Line Items]
Unrealized gains	$ 202		$ 93		$ 621		$ 583
Net income	202		93		621		583
Prior service benefit	109	[1]	92	[1]	325	[1]	275	[1]
Net income	109		92		325		275
Total reclassifications	$ 311		$ 185		$ 946		$ 858

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