Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ in Millions
 3 Months Ended 12 Months Ended
Aug. 31, 2020
USD ($)
segment
Aug. 31, 2019
USD ($)
May 31, 2021
USD ($)
May 31, 2020
USD ($)
Accounting Policies [Line Items]        
Number of reportable segments | segment 1      
Allowance for doubtful accounts $ 11.5     $ 12.5
Advance collections 20.1     6.1
Maximum individual health insurance claims liability       0.3
Stock-based compensation expense 13.3 $ 10.5    
Forecast [Member]        
Accounting Policies [Line Items]        
Maximum individual health insurance claims liability     $ 0.3  
Trade Receivables [Member]        
Accounting Policies [Line Items]        
Receivables 89.8     84.7
Purchased Receivables [Member]        
Accounting Policies [Line Items]        
Receivables $ 336.5     311.9
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