Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2024	Jan. 31, 2023	Jan. 31, 2024	Jan. 31, 2023
Lessee, Lease, Description [Line Items]
Operating leases, rent expense	$ 454	$ 475	$ 1,400	$ 1,400
Weighted average remaining lease term (in years)	4 years 11 months 23 days		4 years 11 months 23 days
Weighted average discount rate, percent	5.88%		5.88%
Corporate Headquarters
Lessee, Lease, Description [Line Items]
Operating leases, rent expense	$ 19	20	$ 57	62
Rockville, MD
Lessee, Lease, Description [Line Items]
Operating leases, rent expense	422	422	1,300	1,300
Milan Italy
Lessee, Lease, Description [Line Items]
Operating leases, rent expense	$ 13	$ 34	$ 38	$ 81