Business Segments and Major Customer Information Sales to countries outside the United States, primarily to Canada and Brazil (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Segment Reporting Information [Line Items]
Net sales	$ 381,511	$ 314,708	$ 237,782
Applied Technology [Member]
Segment Reporting Information [Line Items]
Net sales	132,632	100,090	86,217
Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales	133,481	105,838	63,783
Aerostar [Member]
Segment Reporting Information [Line Items]
Net sales	52,351	48,787	27,244
Electronic Systems [Member]
Segment Reporting Information [Line Items]
Net sales	71,744	65,852	63,525
Countries Outside the United States [Member]
Segment Reporting Information [Line Items]
Net sales	38,909	24,669	20,237
Countries Outside the United States [Member] | Applied Technology [Member]
Segment Reporting Information [Line Items]
Net sales	32,931	21,349	17,140
Countries Outside the United States [Member] | Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales	3,161	2,200	1,383
Countries Outside the United States [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Net sales	1,282	427	1,219
Countries Outside the United States [Member] | Electronic Systems [Member]
Segment Reporting Information [Line Items]
Net sales	$ 1,535	$ 693	$ 495