Leases - other supplemental information (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Cash paid for amounts included in the measurement of lease obligations
Operating cash flows from operating leases	$ 3,414	$ 3,251
Operating cash flows from finance leases	48	48
Financing cash flows from finance leases	42	47
Total	3,503	3,346
Right-of-use assets obtained in exchange for new lease obligations:
Operating leases	2,765	2,443
Finance leases	0	65
Total	$ 2,765	$ 2,508