Goodwill and Other Intangibles Long-lived asset impairment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss	$ 87	$ 3,813	$ 87	$ 3,813
Vista Reporting Unit [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss				3,813
Aerostar [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss	87		87
Property, Plant and Equipment [Member] | Vista Reporting Unit [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss		554		554
Property, Plant and Equipment [Member] | Aerostar [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss	62		62
Radar Technology and Radar Customers [Member] | Vista Reporting Unit [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived assets, fair value		103		103
Finite-Lived Intangible Assets, Net		3,916		3,916
Long-lived asset impairment loss		3,154		3,154
Radar Technology and Radar Customers [Member] | Aerostar [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived assets, fair value	175		175
Finite-Lived Intangible Assets, Net	262		262
Lighter than Air asset group [Member] | Aerostar [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived assets excess of fair value over carrying value	$ 110,000		$ 110,000
Long-lived asset, percentage fair value exceeds carrying value	800.00%		800.00%
Patented Technology [Member] | Vista Reporting Unit [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss		$ 105		$ 105
Patented Technology [Member] | Aerostar [Member]
Finite-Lived Intangible Assets [Line Items]
Long-lived asset impairment loss	$ 25		$ 25