Annual report pursuant to Section 13 and 15(d)

Service Revenue (Summary of PEO Pass-Through Costs Netted in Revenue) (Details)

v3.21.2
Service Revenue (Summary of PEO Pass-Through Costs Netted in Revenue) (Details) - USD ($)
$ in Millions
12 Months Ended
May 31, 2021
May 31, 2020
May 31, 2019
Service Revenue [Abstract]      
Payroll wages and payroll taxes $ 20,600.0 $ 20,500.0 $ 14,500.0
State unemployment insurance (included in payroll wages and payroll taxes) 119.0 85.7 82.3
Guaranteed cost benefit plans $ 586.4 $ 647.0 $ 451.8