Benefit Plans - Components of Net Periodic Postretirement Benefit Cost (Detail) - Postretirement Benefits [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2016	Jun. 28, 2015	Jul. 03, 2016	Jun. 28, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 350	$ 325	$ 700	$ 650
Interest cost	777	707	1,555	1,415
Recognized net actuarial loss	588	718	1,175	1,435
Amortization of prior service cost	(840)	(840)	(1,680)	(1,680)
Net periodic pension cost	$ 875	$ 910	$ 1,750	$ 1,820