Income Taxes - Significant components of the company's deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Jan. 31, 2020
Current deferred tax assets:
Accounts receivable	$ 412	$ 286
Inventories	1,487	1,152
Accrued vacation	966	778
Insurance obligations	150	205
Warranty obligations	441	454
Postretirement benefits	2,106	2,042
Uncertain tax positions	429	445
Share-based compensation	2,239	1,927
Tax Loss Carryforwards	6,684	3,929
Leases	1,541	962
Other accrued liabilities	1,472	952
Deferred Tax Assets, Gross	17,927	13,132
Deferred Tax Assets, Valuation Allowance	0	(630)
Deferred Tax Assets, Net of Valuation Allowance, Total	17,927	12,502
Deferred tax(liabilities):
Depreciation and amortization	(17,599)	(18,086)
Deferred Tax Liabilities, Leasing Arrangements	(1,541)	(962)
Deferred Tax Liabilities, Other	(518)	(518)
Deferred Tax Liabilities, Gross	(19,658)	(19,566)
Net Deferred Tax (Liability),	$ (1,731)	$ (7,064)