FAIR VALUE, Carrying Amounts and Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Carrying amount
Financial assets:
Bank loans, net	$ 23,788	$ 21,125
Financial liabilities:
Bank deposits - certificates of deposit	880	1,017
Senior notes payable	2,037	2,045
Recurring | Total estimated fair value
Financial assets:
Bank loans, net	23,683	21,191
Financial liabilities:
Bank deposits - certificates of deposit	904	1,056
Senior notes payable	2,457	2,504
Recurring | Level 2 | Total estimated fair value
Financial assets:
Bank loans, net	69	72
Financial liabilities:
Bank deposits - certificates of deposit	0	0
Senior notes payable	2,457	2,504
Recurring | Level 3 | Total estimated fair value
Financial assets:
Bank loans, net	23,614	21,119
Financial liabilities:
Bank deposits - certificates of deposit	904	1,056
Senior notes payable	$ 0	$ 0