Income Taxes - Significant components of the company's deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2020	Jan. 31, 2019
Current deferred tax assets:
Accounts receivable	$ 286	$ 147
Inventories	1,152	1,110
Accrued vacation	778	695
Insurance obligations	205	187
Warranty obligations	454	200
Postretirement benefits	2,042	1,800
Uncertain tax positions	445	487
Share-based compensation	1,927	1,834
Operating Loss Carryforwards, Foreign	3,929	0
Deferred Leases	962	0
Other accrued liabilities	952	913
Deferred Tax Assets, Gross	13,132	7,373
Deferred Tax Assets, Valuation Allowance	630	0
Deferred Tax Assets, Net of Valuation Allowance	(12,502)	(7,373)
Deferred tax(liabilities):
Depreciation and amortization	(18,086)	(8,498)
Deferred Tax Liabilities, Leases	962	0
Deferred Tax Liabilities, Other	(518)	(518)
Deferred Tax Liabilities, Gross	(19,566)	(9,016)
Net Deferred Tax (Liability),	$ (7,064)	$ (1,643)