Annual report pursuant to Section 13 and 15(d)

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

v3.21.2
Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details)
$ / shares in Units, $ in Millions
12 Months Ended
Jul. 08, 2021
$ / shares
Jul. 07, 2021
USD ($)
May 31, 2021
USD ($)
segment
May 31, 2020
USD ($)
May 31, 2019
USD ($)
Accounting Policies [Line Items]          
Number of reportable segments | segment     1    
Cash and cash equivalents     $ 995.2 $ 905.2 $ 673.6
Allowance for doubtful accounts     16.0 12.5  
Advance collections     2.5 6.1  
Goodwill     1,820.7 1,791.1 1,782.6
Goodwill, impairment loss     0.0 0.0 0.0
Impairment of intangible assets with indefinite useful lives     0.0 0.0 0.0
Impairment of long-lived assets     0.0 0.0 0.0
Realized gains or losses from foreign exchange transactions     0.0 0.0 0.0
Impairment loss, assets recognized from the costs to obtain and fufill contracts     0.0 0.0 $ 0.0
Workers' compensation insurance costs in current liabilities     65.3 72.3  
Workers' compensation insurance costs in long-term liabilities     117.8 101.3  
Maximum individual health insurance claims liability     0.3 0.3  
PEO accrued health insurance and dental and vision plan reserves in current liabilities     43.9 36.7  
Operating lease, impairment loss     0.0 0.0  
Subsequent Event [Member]          
Accounting Policies [Line Items]          
Authorization repurchase expiration date   Jan. 31, 2024      
Declared date Jul. 08, 2021        
Quarterly dividend per share | $ / shares $ 0.66        
Payable date Aug. 26, 2021        
Record date Aug. 02, 2021        
Trade Receivables [Member]          
Accounting Policies [Line Items]          
Receivables     98.4 84.7  
Purchased Receivables [Member]          
Accounting Policies [Line Items]          
Receivables     $ 495.9 $ 311.9  
Minimum [Member]          
Accounting Policies [Line Items]          
Payroll funding fees average collection period     35 days    
Minimum [Member] | Finite Lived Assets [Member]          
Accounting Policies [Line Items]          
Amortization period     3 years    
Minimum [Member] | Software [Member]          
Accounting Policies [Line Items]          
Estimated useful lives     3 years    
Minimum [Member] | Software Development [Member]          
Accounting Policies [Line Items]          
Estimated useful lives     12 years    
Maximum [Member]          
Accounting Policies [Line Items]          
Payroll funding fees average collection period     45 days    
Maximum [Member] | Subsequent Event [Member]          
Accounting Policies [Line Items]          
Amount authorize to repurchase   $ 400.0      
Maximum [Member] | Finite Lived Assets [Member]          
Accounting Policies [Line Items]          
Amortization period     12 years    
Maximum [Member] | Software [Member]          
Accounting Policies [Line Items]          
Estimated useful lives     5 years    
Europe [Member] | Revenue [Member] | Geographic Concentration Risk [Member]          
Accounting Policies [Line Items]          
Concentration percentage     1.00% 1.00% 1.00%
Europe [Member] | Long Lived Assets [Member] | Geographic Concentration Risk [Member]          
Accounting Policies [Line Items]          
Concentration percentage     7.00% 5.00%  
PEO And Insurance Solutions [Member]          
Accounting Policies [Line Items]          
Cash and cash equivalents     $ 150.5 $ 136.4  
PEO [Member]          
Accounting Policies [Line Items]          
Maximum individual workers' compensation claims liability     $ 1.0 $ 1.0