BANK LOANS, NET, Credit Quality of Held for Investment Loan Portfolio (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held for investment	$ 43,635	$ 25,314
SBL
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	14	3
Fiscal year before current fiscal year	27	45
Fiscal year two years before current fiscal year	72	12
Fiscal year three years before current fiscal year	44	0
Fiscal year four years before current fiscal year	36	0
Prior	41	0
Revolving loans	15,063	6,046
Total loans held for investment	15,297	6,106
SBL | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	14	3
Fiscal year before current fiscal year	27	45
Fiscal year two years before current fiscal year	72	12
Fiscal year three years before current fiscal year	44	0
Fiscal year four years before current fiscal year	36	0
Prior	41	0
Revolving loans	15,063	6,046
Total loans held for investment	15,297	6,106
SBL | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
SBL | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
SBL | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
C&I loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,022	999
Fiscal year before current fiscal year	1,476	1,273
Fiscal year two years before current fiscal year	1,364	1,260
Fiscal year three years before current fiscal year	1,189	1,492
Fiscal year four years before current fiscal year	1,434	961
Prior	2,288	1,715
Revolving loans	2,400	740
Total loans held for investment	11,173	8,440
C&I loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,011	999
Fiscal year before current fiscal year	1,448	1,273
Fiscal year two years before current fiscal year	1,301	1,180
Fiscal year three years before current fiscal year	1,124	1,408
Fiscal year four years before current fiscal year	1,389	935
Prior	2,200	1,633
Revolving loans	2,380	739
Total loans held for investment	10,853	8,167
C&I loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	10	0
Fiscal year before current fiscal year	28	0
Fiscal year two years before current fiscal year	3	41
Fiscal year three years before current fiscal year	37	0
Fiscal year four years before current fiscal year	0	26
Prior	82	54
Revolving loans	6	1
Total loans held for investment	166	122
C&I loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	60	24
Fiscal year three years before current fiscal year	28	84
Fiscal year four years before current fiscal year	40	0
Prior	6	28
Revolving loans	14	0
Total loans held for investment	149	136
C&I loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	15
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	5	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	5	15
CRE loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,916	533
Fiscal year before current fiscal year	1,346	504
Fiscal year two years before current fiscal year	906	532
Fiscal year three years before current fiscal year	724	786
Fiscal year four years before current fiscal year	898	231
Prior	583	224
Revolving loans	176	62
Total loans held for investment	6,549	2,872
CRE loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,916	533
Fiscal year before current fiscal year	1,345	459
Fiscal year two years before current fiscal year	892	442
Fiscal year three years before current fiscal year	707	652
Fiscal year four years before current fiscal year	816	223
Prior	551	174
Revolving loans	176	62
Total loans held for investment	6,403	2,545
CRE loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	1	45
Fiscal year two years before current fiscal year	0	58
Fiscal year three years before current fiscal year	0	36
Fiscal year four years before current fiscal year	36	0
Prior	2	0
Revolving loans	0	0
Total loans held for investment	39	139
CRE loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	14	32
Fiscal year three years before current fiscal year	17	98
Fiscal year four years before current fiscal year	46	8
Prior	30	50
Revolving loans	0	0
Total loans held for investment	107	188
CRE loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
REIT loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	169	235
Fiscal year before current fiscal year	230	95
Fiscal year two years before current fiscal year	96	109
Fiscal year three years before current fiscal year	53	71
Fiscal year four years before current fiscal year	40	83
Prior	222	273
Revolving loans	782	246
Total loans held for investment	1,592	1,112
REIT loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	169	235
Fiscal year before current fiscal year	230	95
Fiscal year two years before current fiscal year	96	75
Fiscal year three years before current fiscal year	53	60
Fiscal year four years before current fiscal year	40	46
Prior	222	167
Revolving loans	782	237
Total loans held for investment	1,592	915
REIT loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	13
Fiscal year three years before current fiscal year	0	11
Fiscal year four years before current fiscal year	0	33
Prior	0	106
Revolving loans	0	6
Total loans held for investment	0	169
REIT loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	21
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	4
Prior	0	0
Revolving loans	0	3
Total loans held for investment	0	28
REIT loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
Residential mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,986	1,861
Fiscal year before current fiscal year	1,705	1,266
Fiscal year two years before current fiscal year	1,023	640
Fiscal year three years before current fiscal year	479	387
Fiscal year four years before current fiscal year	291	453
Prior	867	691
Revolving loans	35	20
Total loans held for investment	7,386	5,318
Residential mortgage loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,984	1,861
Fiscal year before current fiscal year	1,704	1,266
Fiscal year two years before current fiscal year	1,023	640
Fiscal year three years before current fiscal year	477	386
Fiscal year four years before current fiscal year	290	451
Prior	843	666
Revolving loans	35	20
Total loans held for investment	7,356	5,290
Residential mortgage loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	0
Fiscal year before current fiscal year	1	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	2	0
Fiscal year four years before current fiscal year	0	0
Prior	4	5
Revolving loans	0	0
Total loans held for investment	8	5
Residential mortgage loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	1
Fiscal year four years before current fiscal year	1	2
Prior	20	20
Revolving loans	0	0
Total loans held for investment	22	23
Residential mortgage loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
Tax-exempt loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	264	158
Fiscal year before current fiscal year	169	57
Fiscal year two years before current fiscal year	56	124
Fiscal year three years before current fiscal year	115	204
Fiscal year four years before current fiscal year	192	272
Prior	705	506
Revolving loans	0	0
Total loans held for investment	1,501	1,321
Tax-exempt loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	264	158
Fiscal year before current fiscal year	169	57
Fiscal year two years before current fiscal year	56	124
Fiscal year three years before current fiscal year	115	204
Fiscal year four years before current fiscal year	192	272
Prior	705	506
Revolving loans	0	0
Total loans held for investment	1,501	1,321
Tax-exempt loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
Tax-exempt loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	0	0
Tax-exempt loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Fiscal year two years before current fiscal year	0	0
Fiscal year three years before current fiscal year	0	0
Fiscal year four years before current fiscal year	0	0
Prior	0	0
Revolving loans	0	0
Total loans held for investment	$ 0	$ 0