Selected Balance Sheet Information (Details) - USD ($)		Jul. 31, 2019	Apr. 30, 2019	Feb. 01, 2019	Jan. 31, 2019	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018
Accounts receivable, net:
Trade accounts		$ 58,032,000			$ 53,820,000
Unbilled receivables		3,802,000			1,391,000
Allowance for doubtful accounts		(1,134,000)			(739,000)
Accounts receivable, net		60,700,000			54,472,000
Inventories:
Finished goods		7,274,000			7,629,000
In process		2,481,000			1,103,000
Materials		51,556,000			45,344,000
Inventories		61,311,000			54,076,000
Other current assets:
Insurance policy benefit		73,000			336,000
Income tax receivable		2,837,000			1,045,000
Receivable from sale of investments		0			1,055,000
Prepaid Expense and other		5,817,000			6,300,000
Other current assets		8,727,000			8,736,000
Property, plant and equipment, net:
Property, plant and equipment, net		104,654,000			106,615,000
Other Assets (Noncurrent):
Equity investments		1,283,000			345,000
Operating Lease, Right-of-Use Asset		3,121,000		$ 3,807	0
Deferred Income Taxes, Noncurrent		15,000			16,000
Other		1,370,000			2,963,000
Other assets		5,789,000			3,324,000
Accrued liabilities:
Salaries and related		5,453,000			8,244,000
Benefits		4,826,000			4,751,000
Insurance obligations		1,812,000			1,963,000
Warranties		1,739,000	$ 1,391,000		890,000	$ 1,137,000	$ 1,097,000	$ 1,163,000
Income Taxes		273,000			328,000
Other taxes		1,632,000			2,434,000
Acquisition-related contingent consideration liability, current		1,013,000			1,796,000
Lease liability, current		2,064,000		1,446	0
Other		2,480,000			3,072,000
Accrued liabilities		21,292,000			23,478,000
Other liabilities:
Postretirement benefits		7,691,000			7,678,000
Acquisition-related contingent consideration liability, long-term		2,566,000			2,376,000
Lease liability, noncurrent		2,301,000		$ 2,571	0
Deferred income taxes		3,228,000			1,659,000
Uncertain tax positions		2,691,000			2,670,000
Other, Noncurrent		4,339,000			3,852,000
Other Liabilities, Noncurrent		22,816,000			18,235,000
Land [Member]
Property, plant and equipment, net:
Property, plant and equipment		3,234,000			3,234,000
Building and Building Improvements [Member]
Property, plant and equipment, net:
Property, plant and equipment		81,017,000			81,381,000
Machinery and Equipment [Member]
Property, plant and equipment, net:
Property, plant and equipment		158,475,000			155,463,000
Right-of-use Assets, Financing Leases [Member]
Property, plant and equipment, net:
Property, plant and equipment		873,000			0
Property, plant and equipment, Owned [Member]
Property, plant and equipment, net:
Accumulated depreciation					(133,724,000)
Property, plant and equipment, net	[1]				106,354,000
Property, plant and equipment, Owned and Right-of-Use Assets for financing lease [Member]
Property, plant and equipment, net:
Accumulated depreciation		(138,945,000)
Property, plant and equipment, net	[1]	104,654,000
Assets Held under Capital Leases [Member]
Property, plant and equipment, net:
Property, plant and equipment		0			510,000
Accumulated depreciation		$ 0			(249,000)
Assets owned or held under capital lease [Member]
Property, plant and equipment, net:
Property, plant and equipment, net					$ 106,615,000

[1] The amount of assets held for sale at July 31, 2019, and January 31, 2019, were not material.