FAIR VALUE, Carrying Amounts and Estimated Fair Value of Financial Instruments not Recorded on Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Carrying amount
Financial assets:
Bank loans, net	$ 24,902	$ 21,125
Financial liabilities:
Bank deposits - certificates of deposit	878	1,017
Senior notes payable	2,037	2,045
Recurring | Total estimated fair value
Financial assets:
Bank loans, net	24,955	21,191
Financial liabilities:
Bank deposits - certificates of deposit	898	1,056
Senior notes payable	2,459	2,504
Recurring | Level 2 | Total estimated fair value
Financial assets:
Bank loans, net	116	72
Financial liabilities:
Bank deposits - certificates of deposit	0	0
Senior notes payable	2,459	2,504
Recurring | Level 3 | Total estimated fair value
Financial assets:
Bank loans, net	24,839	21,119
Financial liabilities:
Bank deposits - certificates of deposit	898	1,056
Senior notes payable	$ 0	$ 0