Quarterly report [Sections 13 or 15(d)]

Segment Reporting - Schedule of Total Revenue, Net Income and Significant Expenses Used by the Chief Operating Decision Maker (Details)

v3.25.4
Segment Reporting - Schedule of Total Revenue, Net Income and Significant Expenses Used by the Chief Operating Decision Maker (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Nov. 30, 2025
Nov. 30, 2024
Nov. 30, 2025
Nov. 30, 2024
Segment Reporting Information [Line Items]        
Total revenue $ 1,557.6 $ 1,316.9 $ 3,097.6 $ 2,635.4
Core business operations:        
Depreciation and amortization     218.4 80.7
Non-core business operations:        
Total expenses 985.7 778.8 1,983.8 1,550.6
Interest expense (68.5) (9.5) (136.7) (19.1)
Other income, net 16.8 15.1 40.6 35.1
Income before income taxes 520.2 543.7 1,017.7 1,100.8
Income tax expense 124.8 130.3 238.5 260.0
Net income 395.4 413.4 779.2 840.8
Core [Member]        
Core business operations:        
Compensation-related expenses 525.5 454.4 1,055.5 905.7
PEO direct insurance costs 137.0 130.8 275.6 261.1
Depreciation and amortization 49.1 41.7 97.3 80.7
Other segment items [1] 197.0 $ 151.9 393.5 $ 303.1
Noncore [Member]        
Non-core business operations:        
Acquisition-related costs [2] $ 77.1   $ 161.9  
[1] Other segment items include professional service expense, marketing and advertising expenses, and other overhead expenses.
[2] Acquisition-related costs included in total expenses include the amortization of intangibles acquired in the acquisition of Paycor, compensation costs related to the acquisition and integration of Paycor, including replacement awards, severance, and retention bonuses, and other acquisition-related costs, primarily reflecting third-party professional service fees.