Income Taxes Significant components of the company's deferred tax assets and liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Current deferred tax assets:
Accounts receivable	$ 70	$ 58	$ 103
Inventories	507	452	463
Accrued vacation	1,118	1,248	1,008
Insurance obligations	576	559	485
Warranty obligations	661	595	503
Other accrued liabilities	175	387	171
Deferred tax assets, net, current	3,107	3,299	2,733
Non-current deferred tax assets (liabilities):
Postretirement benefits	2,826	2,571	2,014
Depreciation and amortization	(9,114)	(9,673)	(3,050)
Uncertain tax positions	1,969	1,673	1,426
Share-based compensation	1,613	981	601
Other	253	(70)	(67)
Net Deferred Tax Asset or Liability	(2,453)	(4,518)	924
Net deferred tax asset (liability)	$ 654	$ (1,219)	$ 3,657