Income Taxes - Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Deferred tax assets:
Inventories	$ 13,910	$ 12,247
Other postretirement benefits and accrued items	11,477	9,271
Other reserves	7,782	6,834
Foreign tax attributes	6,250	5,909
State tax attributes, net of federal benefit	21,178	22,395
Stock-based compensation	3,751	3,378
Right of Use Liability	6,034	5,965
Basis difference in unconsolidated affiliates	8,478	6,547
Total deferred tax assets	78,860	72,546
Less valuation allowance	(27,199)	(23,130)
Deferred tax assets, net of valuation allowance	51,661	49,416
Deferred tax liabilities:
Property, plant, and equipment	48,990	47,791
Pension	0	949
Right of Use Asset	6,157	5,967
Other Liabilities	638	311
Total deferred tax liabilities	55,785	55,018
Net deferred tax liabilities	$ (4,124)	$ (5,602)