Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 85,179	$ 98,058	$ 171,675	$ 196,236
Administrative and general expenses	(6,595)	(7,373)	(13,535)	(13,848)
Operating income	6,143	10,570	10,082	25,691
Applied Technology [Member]
Segment Reporting Information [Line Items]
Net sales	35,502	27,371	77,509	69,096
Operating income	6,511	4,849	15,450	18,085
Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales	36,252	57,516	69,650	101,808
Operating income	4,465	10,150	6,072	16,513
Aerostar [Member]
Segment Reporting Information [Line Items]
Net sales	13,465	13,189	24,616	25,379
Operating income	1,751	2,943	2,044	4,939
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(40)	(18)	(100)	(47)
Operating income	11	1	51	2
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net sales	85,179	98,058	171,675	196,236
Operating income	$ 12,738	$ 17,943	$ 23,617	$ 39,539