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
Aug. 31, 2025
May 31, 2025
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost $ 4,950.2 $ 4,948.2
Long-term borrowings, Fair value 5,084.1 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 399.3 398.3
Senior Notes, Series B [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 399.3 399.3
Long-term borrowings, Fair value 400.5 395.5
5-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,485.6 1,484.8
Long-term borrowings, Fair value 1,529.2 1,505.1
7-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,483.3 1,482.7
Long-term borrowings, Fair value 1,533.3 1,504.9
10-Year Fixed Rate Corporate Bonds [Member]    
Debt Instrument [Line Items]    
Long-term borrowings, Amortized cost 1,182.1 1,181.6
Long-term borrowings, Fair value $ 1,221.8 $ 1,201.9