Stockholders' Equity - Exchangeable Shares, Share Repurchase Program and Secondary Public Offering (Details) - USD ($)	3 Months Ended
Jul. 31, 2021	Jul. 31, 2020
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)	85,000	0
Shares repurchased, cost	$ 3,900,000
Remaining amount under repurchase program	50,500,000
Maximum
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount	$ 75,000,000

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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