Pension and Other Postretirement Obligations - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016
Pension Obligations
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,251	$ 1,426	$ 2,343	$ 2,835
Interest cost	1,874	2,424	3,569	4,819
Expected return on plan assets	(2,567)	(3,216)	(4,928)	(6,408)
Amortization of prior service credit	(9)	(9)	(20)	(18)
Actuarial losses	645	709	1,233	1,407
Net periodic benefit cost	1,194	1,334	2,197	2,635
Other Postretirement Obligations
Defined Benefit Plan Disclosure [Line Items]
Service cost	13	16	27	29
Interest cost	329	480	656	847
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	0	(11)	0	(22)
Actuarial losses	23	149	45	231
Net periodic benefit cost	$ 365	$ 634	$ 728	$ 1,085