Quarterly report [Sections 13 or 15(d)]

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

v3.26.1
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 28, 2026
USD ($)
Item
Feb. 28, 2025
USD ($)
Item
Feb. 28, 2026
USD ($)
Item
Segment
Feb. 28, 2025
USD ($)
Item
May 31, 2025
USD ($)
Item
Accounting Policies [Line Items]          
Number of reportable segments | Segment     1    
Workers' Compensation Liability, Current $ 86.3   $ 86.3   $ 80.4
Workers' Compensation Liability, Noncurrent 155.8   155.8   156.4
Advance collections 3.0   3.0   1.8
Maximum individual health insurance claims liability     0.5   $ 0.5
Stock-based compensation costs recognized $ 23.1 $ 17.6 $ 75.4 $ 50.5  
Change in accounting principle, accounting standards update, adopted [true false] false   false    
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