XML 50 R39.htm IDEA: XBRL DOCUMENT v3.19.2
Commitments and Contingencies - Narrative (Details) - USD ($)
 12 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Commitments and Contingencies [Line Items]    
Operating leases, rent expense $ 822,000 $ 657,000
Corporate Headquarters    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 91,000 90,000
Laboratories and Office Space    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 0 59,000
New York Laboratory    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 0 52,000
Rockville, MD    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 604,000 454,000
Gaithersburg, MD    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 41,000 0
Rockville, MD New Location    
Commitments and Contingencies [Line Items]    
Operating leases, rent expense 86,000 $ 0
Minimum    
Commitments and Contingencies [Line Items]    
Royalty fee per tumor sample $ 0  
Royalty payment, as percent of contract price 2.00%  
Maximum    
Commitments and Contingencies [Line Items]    
Royalty fee per tumor sample $ 7,000  
Royalty payment, as percent of contract price 5.00%