Business Segments and Major Customer Information (Details)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Electronic Systems [Member]
Segment Reporting Information [Line Items]
Sales to major customer of segment, percentage	10.00%	13.00%	16.00%
Receivables from major customer, percentage	10.00%	11.00%	13.00%
Engineered Films [Member]
Segment Reporting Information [Line Items]
Sales to major customer of segment, percentage	11.00%
Receivables from major customer, percentage	1.00%