XML 118 R74.htm IDEA: XBRL DOCUMENT v3.19.2
Warranty Reserves Estimated Cost (Details) - USD ($)
12 Months Ended
Apr. 30, 2019
Apr. 30, 2017
Warranty Reserves    
Standard Product Warranty Accrual, Preexisting, Increase (Decrease) $ 491,000  
Product Warranty Expense 240,000  
UAS    
Warranty Reserves    
Product Warranty Expense $ 251,000  
UAS | Warranty reserve.    
Warranty Reserves    
Standard Product Warranty Accrual, Preexisting, Increase (Decrease)   $ 491,000