Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2017	Mar. 27, 2016
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 952	$ 998
Interest cost	4,725	4,606
Expected return on assets	(6,281)	(5,507)
Net amortization and deferrals	2,694	2,132
Net periodic benefit cost	2,090	2,229
Contributions to defined benefit pension plans	700
Expected contributions during the remainder of fiscal year	27,900
Postretirement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	172	132
Interest cost	295	294
Expected return on assets	0	0
Net amortization and deferrals	0	0
Net periodic benefit cost	$ 467	$ 426