Employee Benefit Plans (Components of Net Periodic Benefit Cost (Credit)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 05, 2020	Jun. 30, 2019	Jul. 05, 2020	Jun. 30, 2019
Defined Benefit Pension Benefits [Member]
Components of net periodic benefit cost (credit)
Service cost	$ 1,688	$ 1,629	$ 3,595	$ 3,262
Interest cost	3,138	4,150	6,282	8,309
Expected return on plan assets	(5,371)	(6,161)	(10,755)	(12,337)
Amortization of prior service	0	(38)	0	(77)
Net periodic benefit cost (credit)	(545)	(420)	(878)	(843)
Postretirement Medical Benefits [Member]
Components of net periodic benefit cost (credit)
Service cost	18	22	36	44
Interest cost	23	29	47	58
Expected return on plan assets	(347)	(294)	(694)	(588)
Amortization of prior service	0	0	0	0
Net periodic benefit cost (credit)	$ (306)	$ (243)	(611)	(486)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer			$ 3,400	$ 4,100