AVAILABLE-FOR-SALE SECURITIES, Gross Unrealized Losses and Fair Value and Significant Assumptions (Details) - RJ Bank - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	$ 5,563	$ 4,721
Unrealized losses less than 12 months	(73)	(50)
Estimated fair value 12 months or more	1,309	602
Unrealized losses 12 months or more	(46)	(19)
Total estimated fair value	6,872	5,323
Total unrealized losses	(119)	(69)
Agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	3,976	3,155
Unrealized losses less than 12 months	(40)	(25)
Estimated fair value 12 months or more	367	18
Unrealized losses 12 months or more	(9)	0
Total estimated fair value	4,343	3,173
Total unrealized losses	(49)	(25)
Agency commercial MBS
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	479	645
Unrealized losses less than 12 months	(11)	(13)
Estimated fair value 12 months or more	570	353
Unrealized losses 12 months or more	(26)	(15)
Total estimated fair value	1,049	998
Total unrealized losses	(37)	(28)
Agency CMOs
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	1,104	918
Unrealized losses less than 12 months	(22)	(12)
Estimated fair value 12 months or more	372	231
Unrealized losses 12 months or more	(11)	(4)
Total estimated fair value	1,476	1,149
Total unrealized losses	(33)	(16)
Other securities
Debt Securities, Available-for-sale [Line Items]
Estimated far value less than 12 months	4	3
Unrealized losses less than 12 months	0	0
Estimated fair value 12 months or more	0	0
Unrealized losses 12 months or more	0	0
Total estimated fair value	4	3
Total unrealized losses	$ 0	$ 0