LOANS AND ALLOWANCE FOR CREDIT LOSSES - Schedule of Consumer Lending Asset Quality Indicators-FICO and LTV Ratio (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total	$ 141,755		$ 141,755		$ 82,891
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total	1,198	$ 1,200	3,435	$ 3,477
Consumer
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total	59,781		59,781		49,083
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total	1,136	$ 1,163	3,323	$ 3,359
Consumer \| Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	763		763		0
Year Two	1,386		1,386		0
Year Three	918		918		0
Year Four	510		510		241
Year Five	1,671		1,671		970
Prior	7,139		7,139		2,828
Total	12,387		12,387		4,039
Revolving Loans	0		0		0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current Fiscal Year			0		0
Year Two			0		0
Year Three			0		0
Year Four			0		0
Year Five			0		0
Prior			2		0
Total			2		0
Consumer \| Residential mortgages \| No FICO score available
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	5		5		0
Year Five	74		74		0
Prior	251		251		2
Total	330		330		2
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| Less than 600
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		12
Year Five	12		12		23
Prior	174		174		153
Total	186		186		188
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| 600-679
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	2		2		0
Year Two	4		4		0
Year Three	2		2		0
Year Four	4		4		22
Year Five	28		28		48
Prior	384		384		217
Total	424		424		287
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| 680-759
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	201		201		0
Year Two	331		331		0
Year Three	248		248		0
Year Four	157		157		58
Year Five	521		521		198
Prior	2,075		2,075		689
Total	3,533		3,533		945
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| >=760
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	560		560		0
Year Two	1,051		1,051		0
Year Three	668		668		0
Year Four	344		344		149
Year Five	1,036		1,036		701
Prior	4,255		4,255		1,767
Total	7,914		7,914		2,617
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| No LTV Available
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	5		5		0
Year Five	74		74		0
Prior	252		252		2
Total	331		331		2
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| Less than or equal to 70%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	176		176		0
Year Two	362		362		0
Year Three	199		199		0
Year Four	85		85		214
Year Five	500		500		970
Prior	4,729		4,729		2,824
Total	6,051		6,051		4,008
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| 70.01% - 110%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	587		587		0
Year Two	1,024		1,024		0
Year Three	719		719		0
Year Four	420		420		27
Year Five	1,097		1,097		0
Prior	2,157		2,157		2
Total	6,004		6,004		29
Revolving Loans	0		0		0
Consumer \| Residential mortgages \| Greater than 110%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	1		1		0
Total	1		1		0
Revolving Loans	0		0		0
Consumer \| Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	82		82		0
Year Two	135		135		0
Year Three	111		111		0
Year Four	127		127		41
Year Five	217		217		148
Prior	2,138		2,138		1,608
Total	2,810		2,810		1,797
Revolving Loans	2,413		2,413		1,717
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current Fiscal Year			0		0
Year Two			0		0
Year Three			0		0
Year Four			0		0
Year Five			0		0
Prior			6		2
Total			6		2
Consumer \| Home equity \| No FICO score available
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	1		1		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	1		1		2
Prior	41		41		42
Total	43		43		44
Revolving Loans	25		25		26
Consumer \| Home equity \| Less than 600
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		1
Year Five	1		1		7
Prior	109		109		123
Total	110		110		131
Revolving Loans	98		98		114
Consumer \| Home equity \| 600-679
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	3		3		0
Year Two	5		5		0
Year Three	6		6		0
Year Four	6		6		3
Year Five	7		7		12
Prior	220		220		188
Total	247		247		203
Revolving Loans	218		218		189
Consumer \| Home equity \| 680-759
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	29		29		0
Year Two	48		48		0
Year Three	46		46		0
Year Four	49		49		13
Year Five	75		75		47
Prior	694		694		492
Total	941		941		552
Revolving Loans	797		797		539
Consumer \| Home equity \| >=760
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	50		50		0
Year Two	81		81		0
Year Three	59		59		0
Year Four	72		72		24
Year Five	133		133		80
Prior	1,074		1,074		763
Total	1,469		1,469		867
Revolving Loans	1,275		1,275		849
Consumer \| Home equity \| No LTV Available
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	1		1		0
Year Two	3		3		0
Year Three	2		2		0
Year Four	3		3		1
Year Five	3		3		3
Prior	89		89		44
Total	101		101		48
Revolving Loans	69		69		30
Consumer \| Home equity \| Less than or equal to 70%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	62		62		0
Year Two	92		92		0
Year Three	75		75		0
Year Four	81		81		37
Year Five	127		127		144
Prior	1,762		1,762		1,561
Total	2,199		2,199		1,742
Revolving Loans	1,933		1,933		1,681
Consumer \| Home equity \| 70.01% - 110%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	19		19		0
Year Two	40		40		0
Year Three	34		34		0
Year Four	43		43		3
Year Five	87		87		1
Prior	284		284		2
Total	507		507		6
Revolving Loans	408		408		5
Consumer \| Home equity \| Greater than 110%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current Fiscal Year	0		0		0
Year Two	0		0		0
Year Three	0		0		0
Year Four	0		0		0
Year Five	0		0		0
Prior	3		3		1
Total	3		3		1
Revolving Loans	$ 3		$ 3		$ 1

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Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year, Excluding Loans Held for Sale

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Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Excluding Loans Held for Sale

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Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Excluding Loans Held for Sale

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Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Excluding Loans Held for Sale

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Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Excluding Loans Held for Sale

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Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Excluding Loans Held for Sale

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
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-Publisher FASB
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Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

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Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
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Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

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