Pension and Other Postretirement Obligations - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2016	Jun. 28, 2015	Jul. 03, 2016	Jun. 28, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,426	$ 1,443	$ 2,835	$ 3,227
Interest cost	2,424	2,207	4,819	4,747
Expected return on plan assets	(3,216)	(3,159)	(6,408)	(6,313)
Amortization of prior service credit	(9)	(15)	(18)	(26)
Actuarial losses	709	1,288	1,407	2,574
Net periodic benefit cost	1,334	1,764	2,635	4,209
Other Postretirement Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	16	29	32
Interest cost	480	399	847	802
Amortization of prior service credit	(11)	(25)	(22)	(50)
Actuarial losses	149	123	231	252
Net periodic benefit cost	$ 634	$ 513	$ 1,085	$ 1,036