Leases - Additional Information (Details) - USD ($) $ in Billions	12 Months Ended
	May 31, 2021	May 31, 2020
Lessee Lease Description [Line Items]
Finance and operating leases expiration term	various dates through 2060
Percentage total aircraft fleet leased	3.00%	5.00%
Additional leases not yet commenced, undiscounted future payments	$ 2.5
Minimum [Member]
Lessee Lease Description [Line Items]
Operating lease commencement date	2022
Maximum [Member]
Lessee Lease Description [Line Items]
Operating lease commencement date	2023