Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Commitments and Contingencies [Line Items]
Operating leases, rent expense	$ 99	$ 53
Corporate Headquarters [Member]
Commitments and Contingencies [Line Items]
Operating leases, rent expense	$ 21	21
Lease expiration date	Nov. 30, 2016
Laboratories and Office Space [Member]
Commitments and Contingencies [Line Items]
Operating leases, rent expense	$ 26	20
Lease expiration date	Dec. 30, 2017
New York Laboratory [Member]
Commitments and Contingencies [Line Items]
Operating leases, rent expense	$ 52	$ 12
Lease expiration date	Sep. 30, 2016