LOANS AND ALLOWANCE FOR CREDIT LOSSES - Schedule of Payment Defaults of Prior Modification (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 85	$ 109	$ 248	$ 239
All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	14	14	19	17
Commercial \| CRE \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	0	46	0	46
Commercial \| CRE \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	11	0	11	0
Commercial \| C&I loans \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	0	0	1	8
Commercial \| C&I loans \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	0	13	0	14
Commercial \| Multifamily loans \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	3	0	24	0
Commercial \| Multifamily loans \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	0	0	0	0
Consumer \| Residential mortgages \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	0	0	0	0
Consumer \| Residential mortgages \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	2	0	4	0
Consumer \| Home equity loans and lines of credit \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	0	0	0	0
Consumer \| Home equity loans and lines of credit \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	0	0	1	0
Consumer \| RICs and auto loans \| Payment Deferral Only
Financing Receivable, Modified [Line Items]
Amortized Cost	82	63	223	185
Consumer \| RICs and auto loans \| All other modification types
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 1	$ 1	$ 3	$ 3