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v3.25.2

Investment Securities (Tables) | 6 Months Ended
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Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract] |
Amortized Cost and Approximate Fair Values of Investment Securities | The amortized cost and the approximate fair values of investment securities are summarized as follows:
June 30, 2025 | Amortized Cost |  |  | Gross Unrealized Gains | Gross Unrealized Losses | Estimated Fair Value
Available-for-Sale: |  |  |  |  |  |
U.S. Treasury notes | $ | 245.7 |  |  |  | $ | — |  | $ | (11.8) |  | $ | 233.9 |
State, county, and municipal securities | 249.2 |  |  |  | — |  | (35.8) |  | 213.4 |
Obligations of U.S. government agencies | 213.2 |  |  |  | — |  | (6.5) |  | 206.7 |
U.S. agency commercial mortgage-backed securities | 995.7 |  |  |  | 1.0 |  | (49.6) |  | 947.1 |
U.S. agency residential mortgage-backed securities | 1,198.2 |  |  |  | 1.2 |  | (88.0) |  | 1,111.4 |
U.S. agency collateralized mortgage obligations | 1,072.2 |  |  |  | 1.4 |  | (80.0) |  | 993.6 |
Private mortgage-backed securities | 205.5 |  |  |  | — |  | (23.2) |  | 182.3 |
Collateralized loan obligation | 625.8 |  |  |  | 1.0 |  | — |  | 626.8 |
Corporate securities | 239.0 |  |  |  | — |  | (12.0) |  | 227.0 |
Total | $ | 5,044.5 |  |  |  | $ | 4.6 |  | $ | (306.9) |  | $ | 4,742.2 |
June 30, 2025 | Amortized Cost(1) |  |  | Gross Unrealized Gains | Gross Unrealized Losses | Estimated Fair Value
Held-to-Maturity: |  |  |  |  |  |
U.S. Treasury notes | $ | 100.0 |  |  |  | $ | — |  | $ | (0.1) |  | $ | 99.9 |
State, county, and municipal securities | 175.8 |  |  |  | 0.2 |  | (23.5) |  | 152.5 |
Obligations of U.S. government agencies | 466.8 |  |  |  | — |  | (45.2) |  | 421.6 |
U.S. agency commercial mortgage-backed securities | 369.7 |  |  |  | — |  | (24.8) |  | 344.9 |
U.S. agency residential mortgage-backed securities | 1,013.4 |  |  |  | 0.2 |  | (105.1) |  | 908.5 |
U.S. agency collateralized mortgage obligations | 405.0 |  |  |  | 0.5 |  | (54.1) |  | 351.4 |
Corporate securities | 40.0 |  |  |  | — |  | (1.8) |  | 38.2 |
Total | $ | 2,570.7 |  |  |  | $ | 0.9 |  | $ | (254.6) |  | $ | 2,317.0 |
(1) Amortized cost presented above is net of an allowance for credit losses of $0.7 million and includes $6.9 million of unamortized gains and $14.8 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity, respectively.
December 31, 2024 | Amortized Cost |  |  | Gross Unrealized Gains | Gross Unrealized Losses | Estimated Fair Value
Available-for-Sale: |  |  |  |  |  |
U.S. Treasury notes | $ | 245.0 |  |  |  | $ | — |  | $ | (18.1) |  | $ | 226.9 |
State, county, and municipal securities | 252.0 |  |  |  | — |  | (40.0) |  | 212.0 |
Obligations of U.S. government agencies | 224.1 |  |  |  | — |  | (10.8) |  | 213.3 |
U.S. agency commercial mortgage-backed securities | 1,057.2 |  |  |  | 0.1 |  | (74.5) |  | 982.8 |
U.S. agency residential mortgage-backed securities | 1,301.2 |  |  |  | 0.4 |  | (125.8) |  | 1,175.8 |
U.S. agency collateralized mortgage obligations | 1,156.9 |  |  |  | 0.6 |  | (106.6) |  | 1,050.9 |
Private mortgage-backed securities | 218.1 |  |  |  | — |  | (27.6) |  | 190.5 |
Collateralized loan obligation | 770.7 |  |  |  | 1.3 |  | — |  | 772.0 |
Corporate securities | 249.6 |  |  |  | — |  | (16.7) |  | 232.9 |
Total | $ | 5,474.8 |  |  |  | $ | 2.4 |  | $ | (420.1) |  | $ | 5,057.1 |
December 31, 2024 | Amortized Cost(1) |  |  | Gross Unrealized Gains | Gross Unrealized Losses | Estimated Fair Value |
Held-to-Maturity: |  |  |  |  |  |  |
U.S. Treasury notes | $ | 99.8 |  |  |  | $ | — |  | $ | (0.4) |  | $ | 99.4 |  |
State, county, and municipal securities | 176.3 |  |  |  | 0.2 |  | (26.7) |  | 149.8 |  |
Obligations of U.S. government agencies | 470.1 |  |  |  | — |  | (59.9) |  | 410.2 |  |
U.S. agency commercial mortgage-backed securities | 374.9 |  |  |  | — |  | (33.4) |  | 341.5 |  |
U.S. agency residential mortgage-backed securities | 1,082.5 |  |  |  | — |  | (140.7) |  | 941.8 |  |
U.S. agency collateralized mortgage obligations | 427.8 |  |  |  | — |  | (66.1) |  | 361.7 |  |
Corporate securities | 57.0 |  |  |  | — |  | (2.8) |  | 54.2 |  |
Total | $ | 2,688.4 |  |  |  | $ | 0.2 |  | $ | (330.0) |  | $ | 2,358.6 |  |
(1) Amortized cost presented above is net of an allowance for credit losses of $0.9 million and includes $8.0 million of unamortized gains and $15.9 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity, respectively. |
Maturities of Investment Securities |
| Available-for-Sale |  | Held-to-Maturity
June 30, 2025 | Amortized Cost | Estimated Fair Value |  | Amortized Cost | Estimated Fair Value
Within one year | $ | 103.7 |  | $ | 102.4 |  |  | $ | 108.1 |  | $ | 108.0 |
After one year but within five years | 1,296.0 |  | 1,244.0 |  |  | 446.6 |  | 427.8 |
After five years but within ten years | 1,318.2 |  | 1,247.7 |  |  | 442.0 |  | 397.8 |
After ten years | 2,326.6 |  | 2,148.1 |  |  | 1,574.0 |  | 1,383.4 |
Total | $ | 5,044.5 |  | $ | 4,742.2 |  |  | $ | 2,570.7 |  | $ | 2,317.0 |
Schedule of Unrealized Loss on Investments | The following tables show the gross unrealized losses and fair values of available-for-sale investment securities and the length of time individual investment securities have been in an unrealized loss position as of June 30, 2025 and December 31, 2024.
| Less than 12 Months |  | 12 Months or More |  | Total
June 30, 2025 | Fair Value | Gross Unrealized Losses |  | Fair Value | Gross Unrealized Losses |  | Fair Value | Gross Unrealized Losses
Available-for-Sale: |  |  |  |  |  |  |  |
U.S. Treasury notes | $ | — |  | $ | — |  |  | $ | 233.9 |  | $ | (11.8) |  |  | $ | 233.9 |  | $ | (11.8) |
State, county, and municipal securities | — |  | — |  |  | 211.6 |  | (35.8) |  |  | 211.6 |  | (35.8) |
Obligations of U.S. government agencies | 1.0 |  | — |  |  | 200.7 |  | (6.5) |  |  | 201.7 |  | (6.5) |
U.S. agency commercial mortgage-backed securities | — |  | — |  |  | 898.0 |  | (49.6) |  |  | 898.0 |  | (49.6) |
U.S. agency residential mortgage-backed securities | 32.9 |  | (0.6) |  |  | 1,022.3 |  | (87.4) |  |  | 1,055.2 |  | (88.0) |
U.S. agency collateralized mortgage obligations | 6.8 |  | — |  |  | 936.5 |  | (80.0) |  |  | 943.3 |  | (80.0) |
Private mortgage-backed securities | — |  | — |  |  | 182.2 |  | (23.2) |  |  | 182.2 |  | (23.2) |
Corporate securities | 13.0 |  | — |  |  | 192.1 |  | (12.0) |  |  | 205.1 |  | (12.0) |
Total | $ | 53.7 |  | $ | (0.6) |  |  | $ | 3,877.3 |  | $ | (306.3) |  |  | $ | 3,931.0 |  | $ | (306.9) |
| Less than 12 Months |  | 12 Months or More |  | Total
December 31, 2024 | Fair Value | Gross Unrealized Losses |  | Fair Value | Gross Unrealized Losses |  | Fair Value | Gross Unrealized Losses
Available-for-Sale: |  |  |  |  |  |  |  |
U.S. Treasury notes | $ | — |  | $ | — |  |  | $ | 226.8 |  | $ | (18.1) |  |  | $ | 226.8 |  | $ | (18.1) |
State, county, and municipal securities | — |  | — |  |  | 210.1 |  | (40.0) |  |  | 210.1 |  | (40.0) |
Obligations of U.S. government agencies | 3.6 |  | — |  |  | 206.2 |  | (10.8) |  |  | 209.8 |  | (10.8) |
U.S. agency commercial mortgage-backed securities | 38.1 |  | (0.4) |  |  | 934.9 |  | (74.1) |  |  | 973.0 |  | (74.5) |
U.S. agency residential mortgage-backed securities | 33.7 |  | (1.5) |  |  | 1,086.2 |  | (124.3) |  |  | 1,119.9 |  | (125.8) |
U.S. agency collateralized mortgage obligations | 20.5 |  | (0.3) |  |  | 987.1 |  | (106.3) |  |  | 1,007.6 |  | (106.6) |
Private mortgage-backed securities | — |  | — |  |  | 190.4 |  | (27.6) |  |  | 190.4 |  | (27.6) |
Collateralized loan obligation | 10.0 |  | — |  |  | — |  | — |  |  | 10.0 |  | — |
Corporate securities | 27.5 |  | (0.5) |  |  | 205.5 |  | (16.2) |  |  | 233.0 |  | (16.7) |
Total | $ | 133.4 |  | $ | (2.7) |  |  | $ | 4,047.2 |  | $ | (417.4) |  |  | $ | 4,180.6 |  | $ | (420.1) |

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