Leases - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended
	Jun. 30, 2020	Jul. 31, 2021	Jul. 31, 2020	Apr. 30, 2021	Apr. 01, 2021	Jun. 01, 2020	Mar. 30, 2020
Lessee, Lease, Description [Line Items]
Operating leases, rent expense		$ 452	$ 307
Extension term							6 months
Operating lease right-of-use assets, net		8,329		$ 8,521
Gain (loss) on termination of lease		$ 0	75
Weighted average remaining lease term (in years)		7 years 6 months 18 days
Weighted average discount rate, percent		5.77%
Corporate Headquarters
Lessee, Lease, Description [Line Items]
Operating leases, rent expense		$ 24	20
Rockville, MD
Lessee, Lease, Description [Line Items]
Operating leases, rent expense		292	244
Operating lease right-of-use assets, net						$ 3,800	$ 118
Operating lease liability						$ 3,800	$ 125
Incremental rent expense			8
Additional Expansion Premises
Lessee, Lease, Description [Line Items]
Operating leases, rent expense		130	0
Operating lease right-of-use assets, net					$ 3,300
Operating lease liability					$ 3,300
Rockville, MD New Location
Lessee, Lease, Description [Line Items]
Operating leases, rent expense		$ 0	$ 43
Operating lease right-of-use assets, net	$ 850
Operating lease liability	926
Gain (loss) on termination of lease	$ 75