Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Effect of settlement loss	$ 623	$ 1,322
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,082	941
Interest cost	12,681	14,943
Expected return on plan assets	(12,580)	(19,097)
Amortization of prior service cost	250	214
Amortization of net actuarial loss	6,876	9,034
Effect of settlement loss	623	1,322
Net periodic benefit cost (income)	8,932	7,357
Retiree Health and Life Insurance Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	83	74
Interest cost	84	118
Expected return on plan assets	(90)	(177)
Amortization of prior service cost	(68)	(123)
Amortization of net actuarial loss	(197)	(193)
Net periodic benefit cost (income)	$ (188)	$ (301)