FAIR VALUE, Carrying Amounts and Estimated Fair Value of Financial Instruments not Recorded on Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Carrying amount
Financial assets:
Bank loans, net	$ 21,125	$ 20,783
Financial liabilities:
Bank deposits - certificates of deposit	1,017	605
Senior notes payable	2,045	1,550
Recurring | Total estimated fair value
Financial assets:
Bank loans, net	21,191	20,785
Financial liabilities:
Bank deposits - certificates of deposit	1,056	617
Senior notes payable	2,504	1,760
Recurring | Level 2 | Total estimated fair value
Financial assets:
Bank loans, net	72	75
Financial liabilities:
Bank deposits - certificates of deposit	0	0
Senior notes payable	2,504	1,760
Recurring | Level 3 | Total estimated fair value
Financial assets:
Bank loans, net	21,119	20,710
Financial liabilities:
Bank deposits - certificates of deposit	1,056	617
Senior notes payable	$ 0	$ 0