Adoption of Accounting Standards Codification 606 - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Income	$ 2,600	$ 2,115
Other Comprehensive Income, Net of Tax:
Amortization of actuarial losses and prior service costs, net of tax benefit of $45 and $63 for the three months ended March 31, 2018 and April 1, 2017, respectively	141	140
Change in unrealized gains and losses on cash flow hedges, net of tax of $61 and $72 for the three months ended March 31, 2018 and April 1, 2017, respectively	194	(121)
Other Comprehensive Income	335	19
Comprehensive Income	2,935	2,134
Amortization of actuarial losses and prior service costs, tax benefits	45	63
Change in unrealized gains and losses on cash flow hedges, tax benefit	61	$ 72
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Income	(1,718)
Other Comprehensive Income, Net of Tax:
Amortization of actuarial losses and prior service costs, net of tax benefit of $45 and $63 for the three months ended March 31, 2018 and April 1, 2017, respectively	0
Change in unrealized gains and losses on cash flow hedges, net of tax of $61 and $72 for the three months ended March 31, 2018 and April 1, 2017, respectively	0
Other Comprehensive Income	0
Comprehensive Income	(1,718)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Income	882
Other Comprehensive Income, Net of Tax:
Amortization of actuarial losses and prior service costs, net of tax benefit of $45 and $63 for the three months ended March 31, 2018 and April 1, 2017, respectively	141
Change in unrealized gains and losses on cash flow hedges, net of tax of $61 and $72 for the three months ended March 31, 2018 and April 1, 2017, respectively	194
Other Comprehensive Income	335
Comprehensive Income	$ 1,217