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Long-Term Debt and Other Borrowed Funds - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Other Short-term Borrowings	$ 0.0	$ 1,567.5
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(2.8)
5.01% fixed rate borrowings in tenors up to one-month
Fixed-to-floating rate (percent)		4.77%
Notes Payable to FHLB | Subsidiaries | Federal Home Loan Bank Advances
Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds	5,057.3
Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available	$ 5,061.2

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Contractual interest rate for funds borrowed, under the debt agreement.

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