Business Segments and Major Customer Information - Sales to countries outside the United States (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 85,761	$ 100,533	$ 98,058	$ 98,178	$ 88,022	$ 104,833	$ 102,684	$ 111,129	$ 382,530	$ 406,668	$ 377,317
All foreign [Member]
Segment Reporting Information [Line Items]
Net sales									42,132	48,329	41,556
Canada
Segment Reporting Information [Line Items]
Net sales									12,121	12,492	12,940
Europe
Segment Reporting Information [Line Items]
Net sales									14,681	15,786	13,864
Latin America
Segment Reporting Information [Line Items]
Net sales									8,261	5,950	4,439
Asia
Segment Reporting Information [Line Items]
Net sales									3,387	7,240	4,074
Other foreign sales
Segment Reporting Information [Line Items]
Net sales									3,682	6,861	6,239
United States
Segment Reporting Information [Line Items]
Net sales									$ 340,398	$ 358,339	$ 335,761