Earnings Per Common Share - Additional Information (Details)	3 Months Ended	6 Months Ended
Oct. 31, 2019 $ / shares shares	Oct. 31, 2018 shares	Oct. 31, 2019 shares	Oct. 31, 2018 shares
Earnings Per Share [Line Items]
Ratio Of Shares Exchanged For Shares			1
Options to purchase excluded (in shares)	12,174	12,000	330,620	6,065
Options to purchase outstanding (in shares)	4,333,117	4,119,923	4,333,117	4,119,923
Class A Common Shares
Earnings Per Share [Line Items]
Dividends preference (in usd per share) \| $ / shares	$ 0.05

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