Segment Reporting (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Segment Reporting Information [Line Items]
Net sales		$ 86,610	$ 67,598	$ 180,145	$ 135,958
Operating income		11,700	6,696	29,919	14,746
Administrative and general expenses	[1]	(5,887)	(4,884)	(11,257)	(9,222)
Applied Technology [Member]
Segment Reporting Information [Line Items]
Net sales		28,424	22,668	68,914	54,124
Operating income	[2]	6,637	5,172	20,090	13,865
Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales		49,028	36,656	92,583	65,756
Operating income	[2]	9,551	6,659	18,271	10,537
Aerostar [Member]
Segment Reporting Information [Line Items]
Net sales		9,369	8,415	18,975	16,310
Operating income	[2]	1,388	(251)	2,806	(429)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	[3]	(211)	(141)	(327)	(232)
Operating income	[3]	11	0	9	(5)
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating income		$ 17,587	$ 11,580	$ 41,176	$ 23,968

[1] (c) At the segment level, operating income (loss) 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] (b) At the segment level, operating income (loss) does not include an allocation of general and administrative expenses.

[3]
^(a) Intersegment sales for both fiscal 2018 and 2017 were primarily sales from Engineered Films to Aerostar.