Accumulated Other Comprehensive Loss - Summary of Impact of Accumulated Other Comprehensive Income Loss on Income Statement (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	$ 1,164	$ 932	$ 2,328	$ 1,864
Income tax expense	456	366	913	733
Total after tax effect	708	566	1,415	1,131
Cost of Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	118	105	229	210
S,D&A Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	1,046	827	2,099	1,654
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	842	699	1,684	1,397
Income tax expense	330	275	660	550
Total after tax effect	512	424	1,024	847
Pension Plans [Member] | Cost of Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	76	77	152	154
Pension Plans [Member] | S,D&A Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	766	622	1,532	1,243
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	322	233	644	467
Income tax expense	126	91	253	183
Total after tax effect	196	142	391	284
Postretirement Benefits [Member] | Cost of Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	42	28	77	56
Postretirement Benefits [Member] | S,D&A Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Subtotal pre-tax	$ 280	$ 205	$ 567	$ 411