AVAILABLE FOR SALE SECURITIES, Gross Unrealized Losses and Fair Value and Significant Assumptions (Details) - RJ Bank - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Estimated fair value less than 12 months	$ 1,553	$ 313
Unrealized losses less than 12 months	(5)	(1)
Estimated fair value 12 months or more	0	509
Unrealized losses 12 months or more	0	(3)
Total estimated fair value	1,553	822
Unrealized losses	(5)	(4)
Agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Estimated fair value less than 12 months	966	166
Unrealized losses less than 12 months	(3)	0
Estimated fair value 12 months or more	0	114
Unrealized losses 12 months or more	0	(1)
Total estimated fair value	966	280
Unrealized losses	(3)	(1)
Agency commercial MBS
Debt Securities, Available-for-sale [Line Items]
Estimated fair value less than 12 months	177	0
Unrealized losses less than 12 months	(1)	0
Estimated fair value 12 months or more	0	44
Unrealized losses 12 months or more	0	0
Total estimated fair value	177	44
Unrealized losses	(1)	0
Agency CMOs
Debt Securities, Available-for-sale [Line Items]
Estimated fair value less than 12 months	410	145
Unrealized losses less than 12 months	(1)	(1)
Estimated fair value 12 months or more	0	351
Unrealized losses 12 months or more	0	(2)
Total estimated fair value	410	496
Unrealized losses	$ (1)	(3)
Other securities
Debt Securities, Available-for-sale [Line Items]
Estimated fair 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
Unrealized losses		$ 0