Summary of Accounting Policies (Details) - Revenue from External Customers by Products and Services - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Revenue from External Customer [Line Items]
Revenue	$ 41,507	$ 49,509
Satellite Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	20,422	22,810
Government Non-Space Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	16,939	22,771
Other Commercial & Industrial Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	$ 4,146	$ 3,928