Earnings Per Share - Summary of Potentially Dilutive Stock-based Instruments (Details) - shares	12 Months Ended
Apr. 30, 2020	Apr. 30, 2019
Class of Stock [Line Items]
Total common stock equivalents	2,271,658	4,095,066
Stock options
Class of Stock [Line Items]
Total common stock equivalents	2,271,658	2,423,626
Warrants
Class of Stock [Line Items]
Total common stock equivalents	0	1,671,440

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration