Segment Reporting (Details) - USD ($) $ in Thousands		3 Months Ended					9 Months Ended
		Oct. 31, 2016		Oct. 31, 2015		Jul. 31, 2015	Oct. 31, 2016		Oct. 31, 2015
Segment Reporting Information [Line Items]
Goodwill impairment loss		$ 0		$ 11,497			$ 0		$ 11,497
Net sales		72,522		67,611			208,480		205,402
Operating income		7,389		(9,823)			22,135		3,820
Administrative and general expenses		(4,764)		(3,802)			(13,986)		(13,322)
Long-lived asset impairment loss		87		3,813			87		3,813
Applied Technology [Member]
Segment Reporting Information [Line Items]
Gain (Loss) on Disposition of Assets		161		0			161		611
Net sales		25,203		21,344			79,327		74,165
Operating income		6,415	[1]	3,299	[2]		20,280	[1]	16,081	[2]
Engineered Films [Member]
Segment Reporting Information [Line Items]
Net sales		38,551		36,919			104,307		104,029
Operating income		7,129		6,145			17,666		15,981
Aerostar [Member]
Segment Reporting Information [Line Items]
Gain (Loss) on Disposition of Assets									(70)
Net sales		9,003		9,456			25,313		27,338
Operating income		(1,375)		(15,474)	[3]		(1,804)		(15,013)	[3]
Long-lived asset impairment loss		87					87
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	[4]	(235)		(108)			(467)		(130)
Operating income	[4]	(16)		9			(21)		93
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating income		12,153		(6,021)			36,121		17,142
Vista Research [Member]
Segment Reporting Information [Line Items]
Goodwill impairment loss									11,497
Long-lived asset impairment loss									3,813
Cost of Sales [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Inventory Write-down		2,278		0			2,278		0
Cost of Sales [Member] | Vista Research [Member]
Segment Reporting Information [Line Items]
Pre-contract deferred costs written off		0		2,933			$ 0		2,933
Pre-contract costs deferred to inventory		$ 858		$ 858		$ 2,075			2,933
Vista Research [Member] | Cost of Sales [Member]
Segment Reporting Information [Line Items]
Reduction in fair value of contingent consideration liability									$ 2,273

[1] (b) Includes $161 gain for the nine-month period ended October 31, 2016 on the disposal of an idle manufacturing plant held for sale.

[2] (c) Includes gains of $611 for the nine-month period ended October 31, 2015 on disposal of assets related to the exit of contract manufacturing operations.

[3] (e) The three- and nine-month periods ended October 31, 2016 include inventory write-downs of $2,278 as a result of changes in expected sales of a specific product line within radar business.

[4] (a) Intersegment sales for both fiscal 2017 and 2016 were primarily sales from Engineered Films to Aerostar.