Accumulated Other Comprehensive Loss - Summary of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	$ (89,081)	$ (57,421)	$ (89,914)	$ (58,176)
Pre-tax Activity	681	638	2,039	1,870
Tax Effect	(259)	(247)	(784)	(724)
Ending, balance	(88,659)	(57,030)	(88,659)	(57,030)
Net Pension Activity [Member] \| Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(73,890)	(42,510)	(74,867)	(43,028)
Pre-tax Activity	795	450	2,386	1,294
Tax Effect	(305)	(173)	(919)	(499)
Ending, balance	(73,400)	(42,233)	(73,400)	(42,233)
Net Pension Activity [Member] \| Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(88)	(110)	(99)	(121)
Pre-tax Activity	9	9	27	27
Tax Effect	(2)	(4)	(9)	(11)
Ending, balance	(81)	(105)	(81)	(105)
Net Postretirement Benefits Activity [Member] \| Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(21,878)	(17,750)	(22,759)	(18,441)
Pre-tax Activity	717	562	2,152	1,688
Tax Effect	(275)	(218)	(829)	(653)
Ending, balance	(21,436)	(17,406)	(21,436)	(17,406)
Net Postretirement Benefits Activity [Member] \| Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	6,780	2,945	7,812	3,410
Pre-tax Activity	(840)	(377)	(2,520)	(1,133)
Tax Effect	322	146	970	437
Ending, balance	6,262	2,714	6,262	2,714
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning, balance	(5)	4	(1)	4
Pre-tax Activity	0	(6)	(6)	(6)
Tax Effect	1	2	3	2
Ending, balance	$ (4)	$ 0	$ (4)	$ 0

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References + Details