Business Segments and Major Customer Information - Segment reporting information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014		Jan. 31, 2013
Segment Reporting Information [Line Items]
Sales	$ 378,153	$ 394,677		$ 406,175
Operating income	43,801	63,994		77,692
Assets	362,873	301,819		273,210
Capital expenditures	17,041	30,701		29,675
Depreciation and amortization	17,369	14,195		13,098
Corporate & Other [Member]
Segment Reporting Information [Line Items]
Operating income	(21,704)	(18,865)	[1]	(17,293)	[1]
Assets	74,960	74,116	[1]	62,843	[1]
Capital expenditures	2,523	7,189	[1]	5,275	[1]
Depreciation and amortization	2,230	1,439	[1]	1,138	[1]
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	378,153	394,677		406,175
Operating income	65,505	82,859		94,985
Assets	287,913	227,703		210,367
Capital expenditures	14,518	23,512		24,400
Depreciation and amortization	15,139	12,756		11,960
Operating Segments [Member] | Applied Technology [Member]
Segment Reporting Information [Line Items]
Sales	142,154	170,461		171,778
Operating income	34,557	57,000		59,590
Assets	88,764	93,395		84,224
Capital expenditures	3,478	9,324		10,780
Depreciation and amortization	5,569	4,332		3,874
Operating Segments [Member] | Engineered Films [Member]
Segment Reporting Information [Line Items]
Sales	166,634	147,620		141,976
Operating income	21,802	18,154		25,115
Assets	140,023	71,602		65,801
Capital expenditures	8,241	6,681		11,539
Depreciation and amortization	6,096	5,808		5,814
Operating Segments [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Sales	80,772	90,605		102,051
Operating income	8,983	7,816		10,341
Assets	59,274	63,017		60,689
Capital expenditures	2,799	7,507		2,081
Depreciation and amortization	3,474	2,616		2,272
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating income	163	(111)		(61)
Assets	(148)	(311)		(347)
Intersegment Eliminations [Member] | Applied Technology [Member]
Segment Reporting Information [Line Items]
Sales	(231)	(386)		(974)
Intersegment Eliminations [Member] | Engineered Films [Member]
Segment Reporting Information [Line Items]
Sales	(652)	(505)		(124)
Intersegment Eliminations [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Sales	$ (10,524)	$ (13,118)		$ (8,532)

[1] Assets are principally cash, investments, deferred taxes and other receivables.