SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Premises and Equipment) (Details) $ in Millions	3 Months Ended		12 Months Ended		168 Months Ended	180 Months Ended
	Dec. 31, 2025 USD ($) shares	Sep. 30, 2023 USD ($)	Dec. 31, 2025 USD ($) branch machine loan shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2025 USD ($) shares	Dec. 31, 2023 USD ($)
Accounting Policies [Line Items]
Investments in unconsolidated subsidiaries accounted for under the equity methods	$ 0.1		$ 0.1	$ 0.1	$ 0.1	$ 0.1
Intangible assets				$ 1.5	$ 1.5
Impairment, Intangible Asset, Statement Of Income Or Comprehensive Income, Extensible Enumeration, Not Disclosed, Flag	impairment
Impairment of intangible assets	$ 1.3
Number of shares authorized for repurchase (in shares) | shares	185,000,000		185,000,000			185,000,000
Shares of common stock repurchased (in shares) | shares			788,261	49,960	16,734,245	17,522,506
Proportional amortization investments	$ 58.5		$ 58.5	$ 48.7	$ 48.7	$ 58.5
Investments in unconsolidated subsidiaries accounted for under the cost methods	$ 2.7		$ 2.7	$ 3.6	$ 3.6	$ 2.7
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued interest receivable		Accrued interest receivable	Accrued interest receivable	Accrued interest receivable	Accrued interest receivable
Available for sale accrued interest receivable	$ 3.4		$ 3.4	$ 3.6	$ 3.6	$ 3.4
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued interest receivable		Accrued interest receivable	Accrued interest receivable	Accrued interest receivable	Accrued interest receivable
Held-to-maturity accrued interest receivable	$ 1.0		$ 1.0	$ 1.1	$ 1.1	$ 1.0
Number of types of loans held for sale | loan			2
Accrued interest receivable on loans	$ 18.3		$ 18.3	$ 17.5	$ 17.5	$ 18.3
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued interest receivable		Accrued interest receivable	Accrued interest receivable	Accrued interest receivable	Accrued interest receivable
Maximum | Office buildings and improvements
Accounting Policies [Line Items]
Useful life	39 years		39 years			39 years
Maximum | Equipment
Accounting Policies [Line Items]
Useful life	7 years		7 years			7 years
Minimum | Office buildings and improvements
Accounting Policies [Line Items]
Useful life	5 years		5 years			5 years
Minimum | Equipment
Accounting Policies [Line Items]
Useful life	1 year		1 year			1 year
Swell Financial, Inc.
Accounting Policies [Line Items]
Proceeds from intellectual property rights and platform usage fees from products			$ 1.5
Swell Financial, Inc. | Maximum
Accounting Policies [Line Items]
Proceeds from sale of equity method in investment securities	$ 0.5	$ 0.5
Proceeds from intellectual property rights and platform usage fees from products		$ 1.5
Gentry Home Loans LLC
Accounting Policies [Line Items]
Ownership interest	50.00%		50.00%			50.00%
Island Pacific HomeLoans, LLC
Accounting Policies [Line Items]
Ownership interest	50.00%		50.00%			50.00%
Haseko Home Loans LLC
Accounting Policies [Line Items]
Ownership interest	50.00%		50.00%			50.00%
JAM FINTOP Banktech Fund, L.P.
Accounting Policies [Line Items]
Investments in unconsolidated subsidiaries accounted for under the equity methods							$ 2.0
Central Bank
Accounting Policies [Line Items]
Number of branches | branch			27
Number of ATMs | machine			55