Goodwill, Long-lived Assets and Other Intangibles Goodwill, Long-lived Assets, and Other Intangibles (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Apr. 30, 2017 USD ($) ReportingUnits	Apr. 30, 2016 USD ($) ReportingUnits	Jan. 31, 2016 ReportingUnits
Goodwill [Line Items]
Number of Reporting Units	3	3
Number of reporting units in Aerostar Segment		1	2
Aerostar [Member]
Goodwill [Line Items]
Goodwill impairment loss | $	$ 0	$ 0