Income Taxes Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 28, 2019	Dec. 29, 2018
Deferred tax assets:
Inventories	$ 3,336	$ 4,128
Retirement benefits	1,394	1,718
State net operating losses	3,362	4,142
Federal net operating losses	715	4,560
State tax credit carryforwards	1,688	1,688
Federal tax credit carryforwards	4,282	3,721
Allowances for bad debts, claims and discounts	1,978	2,199
Other	4,039	5,646
Total deferred tax assets	20,794	27,802
Valuation allowance	(13,264)	(16,993)
Net deferred tax assets	7,530	10,809
Deferred tax liabilities:
Property, plant and equipment	7,621	11,377
Total deferred tax liabilities	7,621	11,377
Net deferred tax liability	$ (91)	$ (568)