Financing Arrangements - Additional Information (Details)	6 Months Ended
	Nov. 30, 2024 USD ($) AirCraft	May 31, 2024 USD ($)
Line Of Credit Facility [Line Items]
Number of Boeing aircraft | AirCraft	19
Net book value of Boeing aircraft	$ 1,600,000,000
Financial covenant terms ratio	3.50%
Financial covenant compliance ratio	1.80%
Long term debt, including current maturities and exclusive of finance leases carrying value	$ 19,600,000,000	$ 19,800,000,000
Long term debt, including current maturities and exclusive of finance leases fair value	$ 17,900,000,000	$ 17,500,000,000
Long-term debt weighted-average interest rate	3.50%
Three Year Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of credit facility, term	3 years
Line of credit facility maximum borrowing capacity	$ 1,750,000,000
Line of credit facility, expiration date	2027-03
Letter of credit maximum sublimit amount	$ 125,000,000
Five-Year Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of credit facility, term	5 years
Line of credit facility maximum borrowing capacity	$ 1,750,000,000
Line of credit facility, expiration date	2029-03
Letter of credit maximum sublimit amount	$ 125,000,000
Credit Agreements [Member]
Line Of Credit Facility [Line Items]
Line of credit outstanding	0
Commercial paper outstanding	0
Letter of credit outstanding sublimit unused amount	250,000,000
1.875% due in February 2034 [Member]
Line Of Credit Facility [Line Items]
Debt instrument, face amount	$ 970,000,000
Fixed interest rate	1.875%
Debt instrument, maturity date	2034-02