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Investment Securities - Proceeds from Calls and Sales, Realized Gains and Losses and Interest Income Narrative (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Proceeds from calls and sales of investment securities |  |
Proceeds from calls of investment securities | $ 40.2 | $ 10.3
Proceeds from sales of investment securities | 0.0 | 0.0
Gross realized gains and losses on investment securities |  |
Gross realized gains on sales of investment securities | 0.0 | 0.0
Gross realized losses on sales of investment securities | 0.0 | 0.0
Income tax expense related to the Company's net realized gain on the sale of investment securities | 0.0 | 0.0
Interest income from taxable and nontaxable investment securities |  |
Interest income from taxable investment securities | 26.7 | 29.1
Interest income from non-taxable investment securities | $ 3.1 | $ 3.2

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