Quarterly report [Sections 13 or 15(d)]

Fair Value Measurements (Schedule of Amortized Cost and Fair Value of Borrowings) (Details)

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Fair Value Measurements (Schedule of Amortized Cost and Fair Value of Borrowings) (Details) - USD ($)
$ in Millions
Nov. 30, 2025
May 31, 2025
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost $ 4,952.1 $ 4,948.2
Long-term borrowings, Fair value 5,118.0 5,005.7
Senior Notes, Series A [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 399.9 399.8
Long-term borrowings, Fair value 399.9 398.3
Senior Notes, Series B [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 399.4 399.3
Long-term borrowings, Fair value 402.3 395.5
5-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,486.3 1,484.8
Long-term borrowings, Fair value 1,528.5 1,505.1
7-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,483.9 1,482.7
Long-term borrowings, Fair value 1,544.1 1,504.9
10-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,182.6 1,181.6
Long-term borrowings, Fair value $ 1,243.1 $ 1,201.9