AVAILABLE-FOR-SALE SECURITIES, Available-For-Sale Securities in a Continuous Unrealized Loss Position (Details) - RJ Bank - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 241	$ 515
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	5,737	7,311
Unrealized losses, 12 months or more	(532)	(653)
Fair value	5,978	7,826
Unrealized losses	(532)	(653)
Agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	23	0
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	2,994	3,679
Unrealized losses, 12 months or more	(265)	(327)
Fair value	3,017	3,679
Unrealized losses	(265)	(327)
Agency commercial MBS
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	0	0
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	1,129	1,287
Unrealized losses, 12 months or more	(85)	(119)
Fair value	1,129	1,287
Unrealized losses	(85)	(119)
Agency CMOs
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	2	30
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	978	1,114
Unrealized losses, 12 months or more	(147)	(170)
Fair value	980	1,144
Unrealized losses	(147)	(170)
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	215	475
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	9	229
Unrealized losses, 12 months or more	0	(2)
Fair value	224	704
Unrealized losses	0	(2)
Other agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	0	10
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	227	539
Unrealized losses, 12 months or more	(2)	(6)
Fair value	227	549
Unrealized losses	(2)	(6)
Non-agency residential MBS
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	0	0
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	380	417
Unrealized losses, 12 months or more	(32)	(27)
Fair value	380	417
Unrealized losses	(32)	(27)
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	0	0
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	15	42
Unrealized losses, 12 months or more	(1)	(2)
Fair value	15	42
Unrealized losses	(1)	(2)
Other
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	1	0
Unrealized losses, less than 12 months	0	0
Fair value, 12 months or more	5	4
Unrealized losses, 12 months or more	0	0
Fair value	6	4
Unrealized losses	$ 0	$ 0