Selected Balance Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Accounts receivable, net:
Trade accounts	$ 56,895us-gaap_AccountsReceivableGrossCurrent	$ 54,962us-gaap_AccountsReceivableGrossCurrent	$ 56,508us-gaap_AccountsReceivableGrossCurrent
Allowance for doubtful accounts	(319)	(319)	(205)
Accounts receivable, net	56,576us-gaap_AccountsReceivableNetCurrent	54,643us-gaap_AccountsReceivableNetCurrent	56,303us-gaap_AccountsReceivableNetCurrent
Inventories:
Finished goods	8,127	7,232	8,571
In process	1,317	2,131	2,675
Materials	45,708	45,502	34,943
Inventories	55,152us-gaap_InventoryNet	54,865us-gaap_InventoryNet	46,189us-gaap_InventoryNet
Other current assets:
Insurance policy benefit	733us-gaap_EstimatedInsuranceRecoveries	733us-gaap_EstimatedInsuranceRecoveries	860us-gaap_EstimatedInsuranceRecoveries
Federal income taxes receivable	713us-gaap_IncomeTaxesReceivable	1,197us-gaap_IncomeTaxesReceivable	0us-gaap_IncomeTaxesReceivable
Prepaid expenses and other	1,648	1,358	936
Other current assets	3,094us-gaap_OtherAssetsCurrent	3,288us-gaap_OtherAssetsCurrent	1,796us-gaap_OtherAssetsCurrent
Property, plant and equipment, net:
Property, plant and equipment, net	117,513us-gaap_PropertyPlantAndEquipmentNet	98,076us-gaap_PropertyPlantAndEquipmentNet	81,238us-gaap_PropertyPlantAndEquipmentNet
Other assets, net:
Investment in affiliate	3,217us-gaap_EquityMethodInvestments	3,684us-gaap_EquityMethodInvestments	4,063us-gaap_EquityMethodInvestments
Other, net	526us-gaap_OtherAssetsMiscellaneous	224us-gaap_OtherAssetsMiscellaneous	206us-gaap_OtherAssetsMiscellaneous
Other assets, net	3,743us-gaap_OtherAssetsNoncurrent	3,908us-gaap_OtherAssetsNoncurrent	4,269us-gaap_OtherAssetsNoncurrent
Accrued liabilities:
Salaries and related	4,063	2,210	4,422
Benefits	5,001	5,538	5,616
Insurance obligations	1,590	1,598	1,723
Warranties	3,120us-gaap_StandardProductWarrantyAccrual	2,525us-gaap_StandardProductWarrantyAccrual	1,888us-gaap_StandardProductWarrantyAccrual	1,699us-gaap_StandardProductWarrantyAccrual
Accrued Income Taxes, Current	536us-gaap_AccruedIncomeTaxesCurrent	362us-gaap_AccruedIncomeTaxesCurrent	114us-gaap_AccruedIncomeTaxesCurrent
Other taxes	1,240us-gaap_AccruedPayrollTaxesCurrent	1,097us-gaap_AccruedPayrollTaxesCurrent	1,139us-gaap_AccruedPayrollTaxesCurrent
Business Combination, Contingent Consideration, Liability, Current	1,375	890	712
Other	2,262us-gaap_OtherAccruedLiabilitiesCurrent	2,028us-gaap_OtherAccruedLiabilitiesCurrent	1,578us-gaap_OtherAccruedLiabilitiesCurrent
Accrued liabilities	19,187us-gaap_AccruedLiabilitiesCurrent	16,248us-gaap_AccruedLiabilitiesCurrent	17,192us-gaap_AccruedLiabilitiesCurrent
Other liabilities:
Postretirement benefits	11,812	7,998	8,072
Business Combination, Contingent Consideration, Liability, Noncurrent	3,631	2,457	2,359
Deferred income taxes	7,091	3,526	2,453
Uncertain tax positions	3,259	6,557	5,818
Other liabilities	25,793us-gaap_OtherLiabilitiesNoncurrent	20,538us-gaap_OtherLiabilitiesNoncurrent	18,702us-gaap_OtherLiabilitiesNoncurrent
Land [Member]
Property, plant and equipment, net:
Property, Plant and Equipment, Gross	11	0	0
Building and Improvements [Member]
Property, plant and equipment, net:
Property, Plant and Equipment, Gross	1,522	0	0
Assets Held-for-sale [Member]
Property, plant and equipment, net:
Accumulated depreciation	(627)	0	0
Property, plant and equipment, net	906	0	0
Land [Member]
Property, plant and equipment, net:
Property, Plant and Equipment, Gross	3,246	2,077	2,077
Building and Improvements [Member]
Property, plant and equipment, net:
Property, Plant and Equipment, Gross	78,140	66,278	52,936
Machinery and Equipment [Member]
Property, plant and equipment, net:
Property, Plant and Equipment, Gross	131,766	114,345	101,645
Assets held for use [Member]
Property, plant and equipment, net:
Accumulated depreciation	(96,545)	(84,624)	(75,420)
Property, plant and equipment, net	116,607	98,076	81,238
Assets held for use [Member] \| Assets Held-for-sale [Member]
Property, plant and equipment, net:
Property, plant and equipment, net	$ 117,513	$ 98,076	$ 81,238

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Aggregate carrying amount, as of the balance sheet date, of noncurrent obligations not separately disclosed in the balance sheet. Noncurrent liabilities are expected to be paid after one year (or the normal operating cycle, if longer).

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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