Selected Balance Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2015	Jan. 31, 2015	Apr. 30, 2014	Jan. 31, 2014
Accounts receivable, net:
Trade accounts	$ 45,686	$ 56,895	$ 55,574
Allowance for doubtful accounts	(453)	(319)	(319)
Accounts receivable, net	45,233	56,576	55,255
Inventories:
Finished goods	9,127	8,127	6,995
In process	2,533	1,317	1,822
Materials	47,321	45,708	46,249
Inventories	58,981	55,152	55,066
Other current assets:
Insurance policy benefit	683	733	808
Federal taxe receivable	0	713	0
Receivable from sale of business	789	0	0
Prepaid Expense and other assets, current	4,889	1,648	3,307
Other current assets	6,361	3,094	4,115
Property, plant and equipment, net:
Property, plant and equipment, net	118,429	117,513	96,745
Other Assets, Noncurrent [Abstract]
Equity Method Investments	3,095	3,217	3,541
Other, net	1,264	526	211
Other assets, net	4,359	3,743	3,752
Accrued liabilities:
Accrued Salaries and related	3,035	4,063	2,517
Accrued benefits	4,655	5,001	5,579
Insurance obligations	1,629	1,590	1,642
Warranties	2,285	3,120	2,654	2,525
Accrued Income Taxes, Current	1,824	536	5,424
Accrued other taxes	936	1,240	1,014
Acquisition-related contingent consideration liability, Current	938	1,375	628
Other	1,433	2,262	1,193
Accrued liabilities	16,735	19,187	20,651
Other liabilities:
Postretirement benefits	11,976	11,812	8,068
Acquisition-related contingent consideration liability, Noncurrent	3,046	3,631	2,056
Deferred income taxes	7,278	7,091	2,531
Uncertain tax positions	3,281	3,259	6,744
Other liabilities	25,581	25,793	19,399
Land [Member]
Property, plant and equipment, net:
Property, plant and equipment	11	11	0
Building and Building Improvements [Member]
Property, plant and equipment, net:
Property, plant and equipment	1,522	1,522	0
Assets Held-for-sale [Member]
Property, plant and equipment, net:
Accumulated depreciation	(627)	(627)	0
Property, plant and equipment, net	906	906	0
Land [Member]
Property, plant and equipment, net:
Property, plant and equipment	3,246	3,246	2,077
Building and Building Improvements [Member]
Property, plant and equipment, net:
Property, plant and equipment	78,661	78,140	66,787
Machinery and Equipment [Member]
Property, plant and equipment, net:
Property, plant and equipment	135,154	131,766	115,997
Assets held for use [Member]
Property, plant and equipment, net:
Accumulated depreciation	(99,538)	(96,545)	(88,116)
Property, plant and equipment, net	117,523	116,607	96,745
Assets held for use [Member] | Assets Held-for-sale [Member]
Property, plant and equipment, net:
Property, plant and equipment, net	$ 118,429	$ 117,513	$ 96,745