v3.26.1
Segment Reporting - Schedule of Total Revenue, Net Income and Significant Expenses Used by the CODM (Details) - USD ($)
$ in Millions
 12 Months Ended
May 31, 2026
May 31, 2025
May 31, 2024
Segment Reporting Information [Line Items]      
Total revenue $ 6,512.0 $ 5,571.7 $ 5,278.3
Core business operations:      
Depreciation and amortization 442.6 209.5 176.5
Non-core business operations:      
Total expenses 4,001.5 3,364.0 3,104.2
Interest expense, excluding Paycor acquisition-related costs (269.5) (71.4) (37.3)
Acquisition-related costs [1]   (34.0)  
Other income, net 69.9 73.6 81.2
Income before income taxes 2,310.9 2,175.9 2,218.0
Income tax expense 550.8 518.6 [2] 527.6 [2]
Net income 1,760.1 1,657.3 1,690.4
Core [Member]      
Core business operations:      
Compensation-related expenses 2,091.9 1,853.0 1,810.4
PEO direct insurance costs 563.2 520.1 471.3
Depreciation and amortization 200.6 168.8 176.5
Other segment items [3] 841.6 659.8 606.5
Noncore [Member]      
Non-core business operations:      
Acquisition-related costs [1] $ 304.2 $ 162.3  
Cost optimization initiatives [4]     $ 39.5
[1] 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. Acquisition-related costs included in interest expense include the amortization of financing fees related to debt instruments associated with the financing of the Paycor acquisition and the excluded components of the initial fair value of the interest rate swaption contracts.
[2] Disclosures for 2025 and 2024 were adjusted for retrospective application of ASU 2023-09. Refer to Note A for further information on the adoption of ASU 2023-09.
[3] Other segment items include professional service expense, marketing and advertising expenses, and other overhead expense.
[4] Cost optimization initiatives include further reductions to our geographic footprint, reprioritization of certain technology investments, and headcount optimization.