BORROWINGS - Long-term Borrowings - Narrative (Details) - USD ($)	Sep. 30, 2025	Sep. 05, 2025	Jun. 15, 2025	Mar. 12, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Minimum deposit	$ 212,000,000				$ 211,000,000
Parent | Fixed-to-Fixed Subordinated Notes at 5.600% | Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount		$ 600,000,000
Debt instrument, stated interest rate	5.60%	5.60%
Parent | Fixed-to-Floating Senior Notes at 5.231% | Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount				$ 500,000,000
Debt instrument, stated interest rate	5.231%			5.231%
Parent | Fixed-to-Fixed Subordinated Notes at 6.254% | Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount				$ 750,000,000
Debt instrument, stated interest rate	6.254%			6.254%
Parent | Fixed-to-Floating Subordinated Notes at 3.375% | Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount			$ 350,000,000
Debt instrument, stated interest rate	3.375%		3.375%