Assets Held for Sale Assets Held for Sale (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Long Lived Assets Held-for-sale [Line Items]
Long-lived asset impairment loss	$ 0	$ 0	$ 259	$ 0
Inventories	50,844	45,502	50,844	45,502	$ 42,336
Other current assets	3,670	4,958	3,670	4,958	2,689
Total current assets	156,109	129,228	156,109	129,228	138,816
Property, plant and equipment, net	105,723	110,706	105,723	110,706	106,324
Goodwill	40,841	40,752	40,841	40,752	40,649	$ 40,672
Amortizable intangible assets, net	11,228	12,888	11,228	12,888	12,048
Other assets	3,295	3,783	3,295	3,783	3,672
TOTAL ASSETS	317,196	297,357	317,196	297,357	301,509
Current liabilities	31,777	25,074	31,777	25,074	28,382
Other long-term liabilities	12,348	13,827	12,348	13,827	13,696
Aerostar [Member]
Long Lived Assets Held-for-sale [Line Items]
Goodwill	737	789	737	789	$ 789	$ 789
Aerostar [Member] | Client private and radar product assets [Member]
Long Lived Assets Held-for-sale [Line Items]
Inventories	3,212		3,212
Other current assets	18		18
Total current assets	3,230		3,230
Property, plant and equipment, net	238		238
Goodwill	102		102
Amortizable intangible assets, net	387		387
Other assets	17		17
TOTAL ASSETS	3,974		3,974
Current liabilities	292		292
Other long-term liabilities	125		125
Total liabilities held for sale	417		417
Operating Income (Loss) [Member] | Aerostar [Member] | Client private and radar product assets [Member]
Long Lived Assets Held-for-sale [Line Items]
Long-lived asset impairment loss	$ 0	$ 0	$ 0	$ 0