Pension and Postretirement Benefits - Components of Net Periodic Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 808	$ 667	$ 1,845	$ 1,352
Interest cost	4,913	3,980	7,118	7,996
Expected return on assets	(5,128)	(5,174)	(7,166)	(10,379)
Settlement	110,777	0	110,777	0
Net amortization and deferrals	5,610	2,965	7,308	5,942
Net periodic benefit cost	116,980	2,438	119,882	4,911
Postretirement
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	178	189	356	377
Interest cost	316	293	632	585
Expected return on assets	0	0	0	0
Settlement	0	0	0	0
Net amortization and deferrals	5	43	10	85
Net periodic benefit cost	$ 499	$ 525	$ 998	$ 1,047