Quarterly report [Sections 13 or 15(d)]

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

v3.25.4
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Nov. 30, 2025
USD ($)
Item
Nov. 30, 2024
USD ($)
Item
Nov. 30, 2025
USD ($)
Item
Segment
Nov. 30, 2024
USD ($)
Item
May 31, 2025
USD ($)
Item
Accounting Policies [Line Items]          
Number of reportable segments | Segment     1    
Allowance for credit losses $ 27.0   $ 27.0   $ 26.0
Receivables 1,382.5   1,382.5   1,356.5
Current liabilities 7,041.1   7,041.1   6,956.3
Workers' Compensation Liability, Current 88.4   88.4   80.4
Workers' Compensation Liability, Noncurrent 158.2   158.2   156.4
Advance collections 2.5   2.5   1.8
Maximum individual health insurance claims liability     0.5   0.5
Stock-based compensation costs recognized $ 25.5 $ 16.4 $ 52.3 $ 32.9  
Change in accounting principle, accounting standards update, adopted [true false] false   false    
Trade Receivables [Member]          
Accounting Policies [Line Items]          
Receivables $ 226.8   $ 226.8   205.4
Purchased Receivables [Member]          
Accounting Policies [Line Items]          
Receivables $ 1,155.7   $ 1,155.7   $ 1,151.1
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]          
Maximum individual workers' compensation claims liability     $ 1.0   $ 1.0
Individual workers' compensation claims liability     1.0   1.0
PEO Aggregate Claims Exceeding $1.0M [Member] | Maximum [Member]          
Accounting Policies [Line Items]          
Maximum individual workers' compensation claims liability     $ 1.0   $ 1.0