SEGMENT INFORMATION, Classified by Major Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Revenues:
Total net revenues	$ 2,873	$ 2,673	$ 5,659	$ 5,454
Pre-tax income
Total pre-tax income	557	433	1,209	991
Total assets:
Total assets	79,180		79,180		$ 80,951
Goodwill:
Goodwill	1,438		1,438		1,422
U.S.
Revenues:
Total net revenues	2,627	2,430	5,167	5,019
Pre-tax income
Total pre-tax income	524	406	1,133	937
Total assets:
Total assets	72,960		72,960		74,428
Goodwill:
Goodwill	1,250		1,250		1,250
Canada
Revenues:
Total net revenues	144	129	278	266
Pre-tax income
Total pre-tax income	36	14	67	32
Total assets:
Total assets	3,460		3,460		3,631
Goodwill:
Goodwill	24		24		23
Europe
Revenues:
Total net revenues	102	114	214	169
Pre-tax income
Total pre-tax income	(3)	$ 13	9	$ 22
Total assets:
Total assets	2,760		2,760		2,892
Goodwill:
Goodwill	$ 164		$ 164		$ 149