AVAILABLE-FOR-SALE SECURITIES, Gross Unrealized Losses and Fair Value and Significant Assumptions (Details) - RJ Bank - USD ($) $ in Millions	Jun. 30, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	$ 433	$ 313
Unrealized losses less than 12 months	(1)	(1)
Estimated fair value 12 months or more	0	509
Unrealized losses 12 months or more	0	(3)
Total estimated fair value	433	822
Total unrealized losses	(1)	(4)
Agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	284	166
Unrealized losses less than 12 months	(1)	0
Estimated fair value 12 months or more	0	114
Unrealized losses 12 months or more	0	(1)
Total estimated fair value	284	280
Total unrealized losses	(1)	(1)
Agency commercial MBS
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months		0
Unrealized losses less than 12 months		0
Estimated fair value 12 months or more		44
Unrealized losses 12 months or more		0
Total estimated fair value		44
Total unrealized losses		0
Agency CMOs
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	149	145
Unrealized losses less than 12 months	0	(1)
Estimated fair value 12 months or more	0	351
Unrealized losses 12 months or more	0	(2)
Total estimated fair value	149	496
Total unrealized losses	$ 0	(3)
Other securities
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months		2
Unrealized losses less than 12 months		0
Estimated fair value 12 months or more		0
Unrealized losses 12 months or more		0
Total estimated fair value		2
Total unrealized losses		$ 0