Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020
Leases [Abstract]
Operating cash flows paid for operating leases	$ 2,750	$ 2,608
Operating cash flows paid for interest portion of finance leases	16	14
Financing cash flows paid for principal portion of finance leases	75	84
Right-of-use assets obtained in exchange for new operating lease liabilities	3,703	1,915
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 126	$ 484