Pension and Other Postretirement Obligations - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Pension Obligations
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 886	$ 932
Interest cost	1,806	2,337
Expected return on plan assets	(3,668)	(3,940)
Amortization of prior service cost	28	44
Actuarial losses (gains)	979	677
Net periodic benefit cost	31	50
Other Postretirement Obligations
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	8
Interest cost	177	202
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Actuarial losses (gains)	(6)	(19)
Net periodic benefit cost	$ 180	$ 191