Selected Balance Sheet Information (Details) - USD ($) $ in Thousands	Oct. 31, 2017	Jul. 31, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Jan. 31, 2016
Accounts receivable, net:
Trade accounts	$ 60,621		$ 43,834	$ 40,257
Allowance for doubtful accounts	(1,048)		(691)	(703)
Accounts receivable, net	59,573		43,143	39,554
Inventories:
Finished goods	7,063		5,438	5,686
In process	1,035		2,288	2,325
Materials	45,383		34,610	34,802
Inventories	53,481		42,336	42,813
Other current assets:
Insurance policy benefit	593		802	776
Income tax receivable	269		604	228
Receivable from sale of business	17		28	71
Prepaid Expense and other	3,031		1,255	1,672
Other current assets	3,910		2,689	2,747
Property, plant and equipment, net:
Accumulated depreciation	(125,315)		(117,018)	(115,726)
Property, plant and equipment, net	105,651		106,324	108,948
Other Assets (Noncurrent):
Equity investments	1,884		2,371	2,346
Deferred Tax Assets, Net, Noncurrent	18		18	65
Other	1,024		1,283	1,335
Other assets	2,926		3,672	3,746
Accrued liabilities:
Salaries and related	6,464		6,286	3,931
Benefits	4,128		3,960	3,720
Insurance obligations	3,106		2,400	2,022
Warranties	1,217	$ 2,265	1,547	1,852	$ 2,076	$ 1,835
Income Taxes	1,668		498	332
Other taxes	1,446		1,540	1,230
Acquisition-related contingent consideration liability, current	815		445	396
Other	2,801		1,379	1,225
Accrued liabilities	21,645		18,055	14,708
Other liabilities:
Postretirement benefits	8,110		8,054	7,714
Acquisition-related contingent consideration liability, long-term	2,016		1,397	1,385
Deferred income taxes	393		1,421	257
Uncertain tax positions	2,584		2,610	2,778
Liabilities, Noncurrent	353		214	0
Other liabilities	13,456		13,696	12,134
Land [Member]
Property, plant and equipment, net:
Property, plant and equipment	3,234		3,054	3,054
Building and Building Improvements [Member]
Property, plant and equipment, net:
Property, plant and equipment	80,009		77,817	78,674
Machinery and Equipment [Member]
Property, plant and equipment, net:
Property, plant and equipment	$ 147,723		$ 142,471	$ 142,946