Income Taxes Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 26, 2015
Deferred tax assets:
Inventories	$ 4,057	$ 3,927
Retirement benefits	3,387	3,337
State net operating losses	3,672	3,563
Federal net operating losses	5,930	4,345
State tax credit carryforwards	1,728	1,731
Federal tax credit carryforwards	3,361	2,943
Allowances for bad debts, claims and discounts	3,442	3,688
Other	5,001	4,856
Total deferred tax assets	30,578	28,390
Valuation allowance	(5,400)	(5,294)
Net deferred tax assets	25,178	23,096
Deferred tax liabilities:
Property, plant and equipment	17,568	18,370
Total deferred tax liabilities	17,568	18,370
Net deferred tax asset	$ 7,610	$ 4,726