Quarterly report pursuant to Section 13 or 15(d)

Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)

v3.21.2
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ in Millions
 3 Months Ended 12 Months Ended
Aug. 31, 2021
USD ($)
item
segment
Aug. 31, 2020
USD ($)
item
May 31, 2022
USD ($)
May 31, 2021
USD ($)
item
Accounting Policies [Line Items]        
Number of reportable segments | segment 1      
Allowance for doubtful accounts $ 12.1     $ 16.0
Advance collections 4.6     2.5
Maximum individual health insurance claims liability       0.3
Stock-based compensation costs recognized 12.4 $ 13.3    
Forecast [Member]        
Accounting Policies [Line Items]        
Maximum individual health insurance claims liability     $ 0.5  
Trade Receivables [Member]        
Accounting Policies [Line Items]        
Receivables 105.9     98.4
Purchased Receivables [Member]        
Accounting Policies [Line Items]        
Receivables $ 480.3     $ 495.9
Accounts And Unbilled Receivables [Member]        
Accounting Policies [Line Items]        
Number of clients creating a credit concentration | item 0     0
Revenue [Member]        
Accounting Policies [Line Items]        
Number of clients creating a credit concentration | item 0 0    
PEO [Member]        
Accounting Policies [Line Items]        
Maximum individual workers' compensation claims liability       $ 1.0
PEO [Member] | Forecast [Member]        
Accounting Policies [Line Items]        
Maximum individual workers' compensation claims liability     1.0  
PEO [Member] | Minimum [Member] | Forecast [Member]        
Accounting Policies [Line Items]        
Individual workers' compensation claims liability     1.0  
PEO Aggregate Claims Exceeding $1.0M [Member] | Maximum [Member] | Forecast [Member]        
Accounting Policies [Line Items]        
Maximum individual workers' compensation claims liability     $ 2.0