Segment Reporting (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Segment Reporting Information [Line Items]
Net sales		$ 98,058	$ 102,684	$ 196,236	$ 213,813
Administrative and general expenses	[1]	(7,373)	(6,819)	(13,848)	(17,222)
Operating income		10,570	16,629	25,691	38,160
Applied Technology [Member]
Segment Reporting Information [Line Items]
Net sales		27,371	30,362	69,096	70,792
Operating income		4,849	8,788	18,085	24,736
Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales	[2]	57,516	58,875	101,808	118,867
Operating income		10,150	10,806	16,513	24,002
Engineered Films [Member] | Hurricane Recovery Film [Member]
Segment Reporting Information [Line Items]
Net sales				823	8,919
Aerostar [Member]
Segment Reporting Information [Line Items]
Net sales		13,189	13,517	25,379	24,418
Operating income		2,943	3,835	4,939	6,640
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	[3]	(18)	(70)	(47)	(264)
Operating income		1	19	2	4
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating income		$ 17,943	$ 23,448	$ 39,539	$ 55,382

[1] At the segment level, operating income does not include an allocation of general and administrative expenses and, as a result, "General and administrative expenses" are reported as a deduction from "Total reportable segment income" to reconcile to "Operating income" reported in the Consolidated Statements of Income and Comprehensive Income.

[2] Hurricane recovery film sales were $823 and $8,919 for the six-month periods ended July 31, 2019 and 2018. Hurricane recovery film sales were not significant in the three-month periods ended July 31, 2019 and 2018, respectively.

[3] Intersegment sales for both fiscal 2020 and 2019 were primarily sales from Engineered Films to Aerostar.