Accumulated Other Comprehensive Loss - Summary of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	$ (89,500)	$ (57,798)	$ (89,914)	$ (58,176)
Pre-tax Activity	683	616	1,358	1,232
Tax Effect	(264)	(239)	(525)	(477)
Ending, balance	(89,081)	(57,421)	(89,081)	(57,421)
Net Pension Activity [Member] | Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(74,378)	(42,769)	(74,867)	(43,028)
Pre-tax Activity	795	422	1,591	844
Tax Effect	(307)	(163)	(614)	(326)
Ending, balance	(73,890)	(42,510)	(73,890)	(42,510)
Net Pension Activity [Member] | Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(94)	(116)	(99)	(121)
Pre-tax Activity	9	9	18	18
Tax Effect	(3)	(3)	(7)	(7)
Ending, balance	(88)	(110)	(88)	(110)
Net Postretirement Benefits Activity [Member] | Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(22,319)	(18,095)	(22,759)	(18,441)
Pre-tax Activity	718	563	1,435	1,126
Tax Effect	(277)	(218)	(554)	(435)
Ending, balance	(21,878)	(17,750)	(21,878)	(17,750)
Net Postretirement Benefits Activity [Member] | Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	7,296	3,178	7,812	3,410
Pre-tax Activity	(840)	(378)	(1,680)	(756)
Tax Effect	324	145	648	291
Ending, balance	6,780	2,945	6,780	2,945
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(5)	4	(1)	4
Pre-tax Activity	1	0	(6)	0
Tax Effect	(1)	0	2	0
Ending, balance	$ (5)	$ 4	$ (5)	$ 4