Goodwil, Long-lived Assets, and Other Charges Inventory write downs and pre-contract costs write downs (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended	12 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Oct. 31, 2015	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Schedule of Inventory write-down [Line Items]
Inventory, Net					$ 42,336	$ 45,839	$ 55,152
Cost of Sales [Member] | Vista Research [Member]
Schedule of Inventory write-down [Line Items]
Pre-contract deferred costs written off		$ 2,933		$ 2,933	0	2,933	0
Amount of Deferred Costs Related to Long-term Contracts		$ 858	$ 2,075
Radar Inventory [Member] | Vista Research [Member]
Schedule of Inventory write-down [Line Items]
Inventory, Net					4,260
Radar Inventory [Member] | Cost of Sales [Member] | Vista Research [Member]
Schedule of Inventory write-down [Line Items]
Inventory Write-down	$ 2,278			$ 2,278	$ 2,278	$ 0	$ 0