Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans (Narrative) (Details)

v3.23.2
Stock-Based Compensation Plans (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
May 31, 2023
May 31, 2022
May 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized for grant 46,500,000    
Shares available for future grants 14,200,000    
Stock-based compensation expense $ 62.6 $ 52.8 $ 52.5
Income tax benefits related to stock-based compensation 12.1 $ 9.8 8.6
Total unrecognized compensation cost related to all unvested stock-based awards $ 97.5    
Weighted-average period in years of all unvested stock-based awards 2 years 8 months 12 days    
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock options granted 300,000    
Contractual life 10 years    
Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Awards granted [1] 600,000    
Outstanding balance 1,400,000 1,300,000  
Performance-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance period 2 years    
Service period 1 year    
Awards granted [1] 100,000    
Outstanding balance 100,000 100,000  
Time-Based Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 1 year    
Awards granted 0    
Outstanding balance 100,000 100,000  
Performance-Based Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance period 2 years    
Service period 1 year    
Awards granted 0    
Outstanding balance 100,000 100,000  
Director [Member] | Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 1 year    
Non-Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period   5 years  
Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Outside Directors [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 1 year    
Tranche One [Member] | Time-Based Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 33.30%    
Tranche One [Member] | Officer [Member] | Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 33.30%    
Tranche One [Member] | Non-Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage   20.00%  
Tranche One [Member] | Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 33.30%    
Employee Stock Purchase Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expense $ 0.0 $ 0.0 $ 0.0
Discount to the market price 5.00% 5.00% 5.00%
Minimum [Member] | Non-Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Maximum [Member] | Non-Executive [Member] | Time-Based RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 5 years    
Maximum [Member] | Employee Stock Purchase Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Discount to the market price 15.00%    
[1] For performance-based RSUs, granted number assumes achievement of performance goals at target. Actual number of shares to be earned may differ from this amount.