Annual report pursuant to Section 13 and 15(d)

Fee Revenue - Additional Information (Detail)

v3.20.2
Fee Revenue - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Apr. 30, 2020
Apr. 30, 2019
Revenue From Contract With Customer [Abstract]    
Contract liabilities, revenue recognized $ 94.1 $ 97.0
Revenue recognized, remaining performance obligation $ 608.5  
Revenue, practical expedient, initial application and transition, completed contract, same reporting period true  
Revenue, remaining performance obligation, optional exemption, performance obligation true