v3.24.1
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 29, 2024
USD ($)
Item
Feb. 28, 2023
USD ($)
Item
Feb. 29, 2024
USD ($)
Item
Segment
Feb. 28, 2023
USD ($)
Item
May 31, 2024
USD ($)
May 31, 2023
USD ($)
Item
Accounting Policies [Line Items]            
Number of reportable segments | Segment     1      
Revision decreased net cash provided by operating activities     $ 1.3      
Revision increased net cash provided by investing activities     1.3      
Allowance for credit losses $ 22.5   22.5     $ 20.5
Advance collections 50.2   50.2     12.5
Maximum individual health insurance claims liability           0.5
Stock-based compensation costs recognized $ 14.4 $ 16.3 $ 45.1 $ 46.0    
Accounting Standards Update 2021-08 [Member]            
Accounting Policies [Line Items]            
Change in accounting principle, accounting standards update, adoption date Jun. 01, 2023   Jun. 01, 2023      
Change in accounting principle, accounting standards update, adopted [true false] true   true      
Change in accounting principle, accounting standards update, immaterial effect [true false] true   true      
Forecast [Member]            
Accounting Policies [Line Items]            
Maximum individual health insurance claims liability         $ 0.5  
Trade Receivables [Member]            
Accounting Policies [Line Items]            
Receivables $ 215.4   $ 215.4     287.0
Purchased Receivables [Member]            
Accounting Policies [Line Items]            
Receivables $ 895.7   $ 895.7     $ 606.8
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 0 0    
PEO Aggregate Claims Exceeding $1.0M [Member] | Minimum [Member]            
Accounting Policies [Line Items]            
Individual workers' compensation claims liability           $ 1.0
PEO Aggregate Claims Exceeding $1.0M [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]            
Accounting Policies [Line Items]            
Maximum individual workers' compensation claims liability           $ 2.0
PEO Aggregate Claims Exceeding $1.0M [Member] | Maximum [Member] | Forecast [Member]            
Accounting Policies [Line Items]            
Maximum individual workers' compensation claims liability         $ 1.0