Employee Benefit Plans (Schedule of Net Benefit Costs, Other Postretirement Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,598	$ 6,853	$ 4,951
Interest cost	16,546	16,146	16,707
Expected return on plan assets	(24,561)	(28,939)	(26,401)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	1,547	0	0
Actuarial loss (gain)	(27,134)	(17,146)	7,085
Amortization of prior service cost	(152)	375	(195)
Net periodic benefit cost	24,018	11,581	(12,023)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	87	106	92
Interest cost	116	120	125
Expected return on plan assets	(1,175)	(1,254)	(1,114)
Defined Benefit Plan, Amortization of Gain (Loss)	(1,776)	1,621	(741)
Actuarial loss (gain)	108	(611)
Net periodic benefit cost	$ (2,748)	$ 593	$ (1,638)