Selected Balance Sheet Information (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Jul. 31, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Jan. 31, 2017
Accounts receivable, net:
Trade accounts	$ 64,942		$ 57,063
Unbilled receivables	1,967		2,447
Allowance for doubtful accounts	(743)		(978)
Accounts receivable, net	66,166		58,532
Inventories:
Finished goods	44,998		46,336
In process	1,040		961
Materials	7,191		8,054
Inventories	53,229		55,351
Other current assets:
Insurance policy benefit	574		759
Income tax receivable	1,370		1,397
Receivable from sale of investments	1,055		0
Prepaid Expense and other	3,475		3,705
Other current assets	6,474		5,861
Property, plant and equipment, net:
Property, plant and equipment, net	106,499		106,280
Other Assets (Noncurrent):
Equity investments	249		1,955
Deferred Income Taxes, Noncurrent	19		19
Other	2,641		976
Other assets	2,909		2,950
Accrued liabilities:
Salaries and related	6,543		9,409
Benefits	4,314		4,225
Insurance obligations	2,626		1,992
Warranties	851	$ 1,137	1,163	$ 1,217	$ 2,265	$ 1,547
Income Taxes	549		226
Other taxes	1,568		1,880
Acquisition-related contingent consideration liability, current	1,764		1,036
Other	3,217		2,015
Accrued liabilities	21,432		21,946
Other liabilities:
Postretirement benefits	8,246		8,264
Acquisition-related contingent consideration liability, long-term	647		2,010
Deferred income taxes	1,472		615
Uncertain tax positions	2,637		2,634
Other, Noncurrent	4,089		272
Other Liabilities, Noncurrent	17,091		13,795
Land [Member]
Property, plant and equipment, net:
Property, plant and equipment	3,234		3,234
Building and Building Improvements [Member]
Property, plant and equipment, net:
Property, plant and equipment	81,191		80,299
Machinery and Equipment [Member]
Property, plant and equipment, net:
Property, plant and equipment	157,570		149,847
Property, plant and equipment, Owned [Member]
Property, plant and equipment, net:
Accumulated depreciation	(135,804)		(127,523)
Property, plant and equipment, net	106,191		105,857
Assets Held under Capital Leases [Member]
Property, plant and equipment, net:
Property, plant and equipment	510		488
Accumulated depreciation	(202)		(65)
Assets owned or held under capital lease [Member]
Property, plant and equipment, net:
Property, plant and equipment, net	$ 106,499		$ 106,280