Benefit Plans - Components of Net Periodic Postretirement Benefit Cost (Detail) - Postretirement Benefits [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 572	$ 350	$ 1,144	$ 700
Interest cost	911	777	1,822	1,555
Recognized net actuarial loss	648	588	1,296	1,175
Amortization of prior service cost	(746)	(840)	(1,492)	(1,680)
Net periodic pension cost	$ 1,385	$ 875	$ 2,770	$ 1,750