Employee Retirement Plans Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020 USD ($)	Sep. 28, 2019 USD ($)	Sep. 26, 2020 USD ($) plan	Sep. 28, 2019 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net Periodic Benefit Cost, Other Components	$ 10,149	$ 7,175	$ 30,004	$ 22,233
Number of defined contribution 401K savings plans | plan			2
Non-US Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	649	593	$ 1,918	1,839
Interest cost	6,456	7,995	19,086	24,776
Expected return on assets	(18,089)	(16,118)	(53,476)	(49,948)
Amortization of net loss (gain)	842	149	2,489	462
Amortization of prior service cost (credit)	642	614	1,897	1,904
Curtailment loss (gain)	0	185	0	573
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (9,500)	$ (6,582)	$ (28,086)	$ (20,394)