Earnings Per Common Share - Additional Information (Details)	3 Months Ended
Jul. 31, 2020 $ / shares shares	Jul. 31, 2019 shares
Earnings Per Share [Line Items]
Share conversion ratio	1
Options to purchase excluded (in shares)	647,935	577,217
Options to purchase outstanding (in shares)	3,959,903	3,873,560
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://www.xbrl.org/2003/role/disclosureRef
-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