Leases - Summary of Components of Net Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020
Leases [Abstract]
Operating lease cost	$ 2,848	$ 2,668
Finance lease cost:
Amortization of right-of-use assets	23	18
Interest on lease liabilities	17	12
Total finance lease cost	40	30
Short-term lease cost	387	197
Variable lease cost	1,318	1,160
Net lease cost	$ 4,593	$ 4,055