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BORROWINGS - Long-term Borrowings - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2026	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Aug. 03, 2026	Jun. 24, 2026	Mar. 03, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ (7,000,000)	$ 0	$ (15,000,000)	$ 0
Minimum deposit		$ 180,000,000		180,000,000					$ 212,000,000
Fixed-to-Floating Senior Notes at 5.097% \| Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount							$ 750,000,000
Debt instrument, stated interest rate							5.097%
Fixed-to-Floating Senior Notes at 5.097% \| Subordinated Debt \| Subsequent Event
Debt Instrument [Line Items]
Debt instrument, face amount						$ 400,000,000
Debt instrument, stated interest rate						5.097%
Fixed-to-Floating Senior Notes at 4.869% \| Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount								$ 500,000,000
Purchase Money Note
Debt Instrument [Line Items]
Partial prepayment				$ 5,000,000,000.00
Purchase Money Note \| Subsequent Event
Debt Instrument [Line Items]
Partial prepayment	$ 1,000,000,000.00
Parent \| Fixed-to-Floating Senior Notes at 4.869% \| Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, stated interest rate								4.869%