Selected Balance Sheet Information (Details) - USD ($) $ in Thousands		Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Accounts receivable, net:
Trade accounts		$ 53,820	$ 57,063
Unbilled receivables		1,391	2,447
Allowance for doubtful accounts		(739)	(978)
Accounts receivable, net		54,472	58,532
Inventories:
Finished goods		7,629	8,054
In process		1,103	961
Materials		45,344	46,336
Inventories		54,076	55,351
Other current assets:
Insurance policy benefit		336	759
Federal income taxes receivable		1,045	1,397
Receivable from sale of investments		1,055	0
Prepaid expenses and other		6,300	3,705
Other current assets		8,736	5,861
Property, plant and equipment, net:
Property, plant and equipment, net		106,615	106,280
Other assets:
Equity investments		345	1,955
Other		2,963	976
Other assets		3,324	2,950
Accrued liabilities:
Salaries and related		8,244	9,409
Benefits		4,751	4,225
Deferred income taxes		16	19
Insurance obligations		1,963	1,992
Warranties		890	1,163	$ 1,547	$ 1,835
Accrued income taxes, current		328	226
Other taxes		2,434	1,880
Acquisition-related contingent liability, current		1,796	1,036
Other		3,072	2,015
Accrued liabilities		23,478	21,946
Other liabilities:
Postretirement benefits		7,678	8,264
Acquisition-related contingent consideration		2,376	2,010
Deferred income taxes		1,659	615
Uncertain tax positions		2,670	2,634
Other		3,852	272
Other liabilities		18,235	13,795
Land
Property, plant and equipment, net:
Property, plant and equipment, gross	[1]	3,234	3,234
Building and Improvements
Property, plant and equipment, net:
Property, plant and equipment, gross	[1]	81,381	80,299
Machinery and Equipment
Property, plant and equipment, net:
Property, plant and equipment, gross	[1]	155,463	149,847
Property, plant and equipment, Held-For-Use and assets Held-For-Sale
Property, plant and equipment, net:
Accumulated amortization for capitalized leases	[1]	(133,724)	(127,523)
Property, plant and equipment, net	[1]	106,354	105,857
Assets Held under Capital Leases
Property, plant and equipment, net:
Machinery and equipment		510	488
Capital leases, lessee balance dheet, assets by major class, accumulated depreciation		(249)	(65)
Capital leases, balance sheet, assets by major class, net		261	423
Assets owned and held under capital lease
Property, plant and equipment, net:
Property, plant and equipment, net	[1]	$ 106,615	$ 106,280

[1] The amount of assets and liabilities held for sale as of January 31, 2019 and 2018 were not material.