Goodwill and Intangible Assets (Narrative) (Details)	3 Months Ended		9 Months Ended	12 Months Ended
	Jan. 31, 2016 USD ($)	Oct. 31, 2015 USD ($)	Oct. 31, 2015 USD ($)	Jan. 31, 2016 USD ($) ReportingUnits	Jan. 31, 2015 USD ($)	Jan. 31, 2014 USD ($)	Jul. 31, 2015 USD ($)	Jan. 31, 2013 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Number of reporting units in Aerostar Segment | ReportingUnits				2
Goodwill [Line Items]
Goodwill	$ 40,672,000			$ 40,672,000	$ 52,148,000	$ 22,274,000		$ 22,274,000
Goodwill impairment loss				11,497,000	0	0
Goodwill gross of accumulated impairment losses	52,169,000			52,169,000	52,148,000	22,274,000
Long-lived asset impairment loss				3,826,000	0	0
Engineered Films [Member]
Goodwill [Line Items]
Excess in carrying value							$ 50,000,000
Goodwill	27,518,000			27,518,000	27,312,000	96,000		96,000
Goodwill impairment loss				0
Vista Reporting Unit [Member]
Goodwill [Line Items]
Carrying value in excess of fair value		$ (13,986,000)	$ (13,986,000)
Excess in carrying value, percentage		(63.60%)	(63.60%)
Goodwill	0			0	11,497,000	11,497,000		$ 11,497,000
Goodwill impairment loss	0	$ 11,497,000	$ 11,497,000	11,497,000	0	0
Long-lived assets, fair value		103,000	103,000
Long-lived assets, carrying value		3,916,000	3,916,000
Long-lived asset impairment loss	13,000	3,813,000	3,813,000	3,826,000	$ 0	$ 0
Vista Reporting Unit [Member] | Radar Technology and Radar Customers [Member]
Goodwill [Line Items]
Long-lived asset impairment loss	0	3,154,000	3,154,000	3,154,000
Vista Reporting Unit [Member] | Patented Technology [Member]
Goodwill [Line Items]
Long-lived asset impairment loss	13,000	105,000	105,000	118,000
Vista Reporting Unit [Member] | Property, Plant and Equipment [Member]
Goodwill [Line Items]
Long-lived asset impairment loss	$ 0	$ 554,000	$ 554,000	$ 554,000