Pension and Postretirement Benefits (Details) $ in Thousands	3 Months Ended
	Apr. 01, 2018 USD ($) plan	Mar. 26, 2017 USD ($)
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and other postretirement benefit	$ (97)	$ (52)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of pension plans | plan	2
Components of net periodic benefit costs:
Service cost	$ 150	157
Interest cost	700	780
Expected return on plan assets	(1,062)	(1,045)
Amortization of unrecognized loss (gain)	67	44
Total	(145)	(64)
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension contributions	107
Expected employer contributions during the current fiscal year	1,658
Postretirement [Member]
Components of net periodic benefit costs:
Service cost	0	1
Interest cost	21	27
Expected return on plan assets	0	0
Amortization of unrecognized loss (gain)	27	(16)
Total	$ 48	$ 12