Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018
Defined Benefit Plan Disclosure [Line Items]
Effect of settlement loss	$ 1,322
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	941	$ 4,672
Interest cost	14,943	13,978
Expected return on plan assets	(19,097)	(23,209)
Amortization of prior service cost	214	249
Amortization of net actuarial loss	9,034	9,420
Effect of settlement loss	1,322	0
Net periodic benefit cost (income)	7,357	5,110
Retiree Health and Life Insurance Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	74	79
Interest cost	118	111
Expected return on plan assets	(177)	(472)
Amortization of prior service cost	(123)	(126)
Amortization of net actuarial loss	(193)	(242)
Net periodic benefit cost (income)	$ (301)	$ (650)