LOAN SERVICING - Schedule of Activity in MSR (Details) - Mortgage Servicing Rights - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Servicing Assets at Fair Value [Line Items]
Mortgage loans sold with servicing retained	$ 6,603.0		$ 6,429.0
Mortgage loans sold with servicing retained	312.0	$ 316.0
Pre-tax net gains (losses) resulting from above loan sales	4.0	6.0
Mortgage servicing fees	4.0	4.0
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	70.5	59.5
Additions	3.5	3.9
Payoffs and curtailments	(0.8)	(0.5)
Impairment (charge) / recovery	(0.1)	0.2
Amortization / other	(0.5)	(0.6)
Balance at end of period	72.6	62.5
Fair value, beginning of period	86.3	71.8
Fair value, end of period	84.8	$ 75.2
Valuation allowance for servicing rights	$ 0.2		$ 0.1

Gain From Sale of Loan, Net, Pretax

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Loans Sold With Servicing Retained

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Servicing Asset at Amortized Cost, Amortization and Other

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Unpaid Principal Balance For Loans Serviced For Investors

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Income from mortgage banking activities (fees and commissions) and servicing real estate mortgages, credit cards, and other financial assets held by others net of any related impairment of capitalized service costs. Also includes any premiums received in lieu of regular servicing fees on such loans only as earned over the life of the loans.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1402
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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount conveyed to unrelated parties of contract to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of increase (decrease) in the amortized amount from a decrease (increase) in the valuation allowance applied to the servicing asset for a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

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