FAIR VALUE, Level 3 Financial Assets and Liabilities, Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Trading liabilities | Other liabilities
Changes in Level 3 curring fair value measurements, liabilities [Roll Forward]
Fair value beginning of year	$ 0	$ (1)
Total gains/(losses) included in earnings		0
Purchases and contributions		2
Sales and distributions		(1)
Transfers:
Into Level 3		0
Out of Level 3		0
Fair value end of year		0
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year		0
Derivative liabilities | Other liabilities
Changes in Level 3 curring fair value measurements, liabilities [Roll Forward]
Fair value beginning of year	(5)	0
Total gains/(losses) included in earnings	5	(5)
Purchases and contributions	0	0
Sales and distributions	(1)	0
Transfers:
Into Level 3	0	0
Out of Level 3	0	0
Fair value end of year	(1)	(5)
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year	(1)	(5)
Trading assets | Other
Changes in Level 3 recurring fair value measurements, assets [Roll Forward]
Fair value beginning of year	12	3
Total gains/(losses) included in earnings	(1)	(4)
Purchases and contributions	49	70
Sales and distributions	(46)	(57)
Transfers:
Into Level 3	0	0
Out of Level 3	0	0
Fair value end of year	14	12
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year	0	(1)
Derivative assets | Other
Changes in Level 3 recurring fair value measurements, assets [Roll Forward]
Fair value beginning of year	0
Total gains/(losses) included in earnings	1
Purchases and contributions	0
Sales and distributions	(1)
Transfers:
Into Level 3	0
Out of Level 3	0
Fair value end of year	0	0
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year	0
Other investments | Other investments - private equity
Changes in Level 3 recurring fair value measurements, assets [Roll Forward]
Fair value beginning of year	37	63
Total gains/(losses) included in earnings	37	(29)
Purchases and contributions	1	4
Sales and distributions	0	(1)
Transfers:
Into Level 3	0	0
Out of Level 3	0	0
Fair value end of year	75	37
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year	37	(29)
Other investments | All other
Changes in Level 3 recurring fair value measurements, assets [Roll Forward]
Fair value beginning of year	22	24
Total gains/(losses) included in earnings	1	(2)
Purchases and contributions	0	0
Sales and distributions	0	0
Transfers:
Into Level 3	0	0
Out of Level 3	0	0
Fair value end of year	23	22
Unrealized gains/(losses) for the year included in earnings for instruments held at the end of the year	$ 1	$ (2)