Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Oct. 31, 2014		Oct. 31, 2013		Oct. 31, 2014		Oct. 31, 2013
Segment Reporting Information [Line Items]
Net sales	$ 91,292		$ 104,938		$ 288,287		$ 302,039
Operating income	10,159		18,132		37,387		51,634
Administrative and general expenses	(4,935)		(4,949)		(15,690)		(14,730)
Applied Technology Division [Member]
Segment Reporting Information [Line Items]
Net sales	33,161		43,797		115,696		134,069
Operating income	6,447		15,149		31,132		46,176
Engineered Films Division [Member]
Segment Reporting Information [Line Items]
Net sales	41,249		40,241		125,755		111,998
Operating income	5,486		5,241		17,165		14,765
Aerostar Division [Member]
Segment Reporting Information [Line Items]
Net sales	19,257		24,269		56,179		66,706
Operating income	3,027		2,714		4,666		5,484
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(2,375)	[1]	(3,369)	[1]	(9,343)	[1]	(10,734)	[1]
Operating income	134	[1]	(23)	[1]	114	[1]	(61)	[1]
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating income	$ 15,094		$ 23,081		$ 53,077		$ 66,364

[1] Intersegment sales were primarily from Aerostar to Applied Technology.