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Securities - Amortized Cost and Fair Value (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 USD ($) item | Dec. 31, 2022 USD ($)
Securities Available-for-Sale |  |
Amortized Cost | $ 1,276,981 | $ 1,662,819
Gross Unrealized Gains | 1,818 | 370
Gross Unrealized Losses | (85,970) | (123,830)
Securities available-for-sale | 1,192,829 | 1,539,359
Accrued interest receivable | 6,600 | 6,800
FHLB and FRB Stock |  |
FHLBC stock | 18,500 | 5,600
FRBC stock | 14,900 | 14,900
Securities pledged to secure deposits and for other purposes | 810,200 | 547,800
Other disclosures |  |
Securities available-for-sale | $ 1,192,829 | 1,539,359
Number of securities issued from originators | 0 |
Number of originators | item | 1 |
Minimum percentage of securities investment | 10.00% |
US government and agencies debt securities, percentage of guarantee | 100.00% |
US government and agencies debt securities, threshold percentage of guarantee for allowance of credit loss | 100.00% |
U.S. Treasury |  |
Securities Available-for-Sale |  |
Amortized Cost | $ 174,602 | 224,054
Gross Unrealized Losses | (5,028) | (11,925)
Securities available-for-sale | 169,574 | 212,129
Other disclosures |  |
Securities available-for-sale | 169,574 | 212,129
U.S. government agencies |  |
Securities Available-for-Sale |  |
Amortized Cost | 60,011 | 61,178
Gross Unrealized Losses | (3,052) | (5,130)
Securities available-for-sale | 56,959 | 56,048
Other disclosures |  |
Securities available-for-sale | 56,959 | 56,048
U.S. government agencies mortgage-backed |  |
Securities Available-for-Sale |  |
Amortized Cost | 118,492 | 140,588
Gross Unrealized Losses | (12,122) | (15,598)
Securities available-for-sale | 106,370 | 124,990
Other disclosures |  |
Securities available-for-sale | 106,370 | 124,990
States and political subdivisions |  |
Securities Available-for-Sale |  |
Amortized Cost | 238,440 | 239,999
Gross Unrealized Gains | 1,325 | 363
Gross Unrealized Losses | (10,430) | (14,234)
Securities available-for-sale | 229,335 | 226,128
Other disclosures |  |
Securities available-for-sale | 229,335 | 226,128
Corporate bonds |  |
Securities Available-for-Sale |  |
Amortized Cost |  | 10,000
Gross Unrealized Losses |  | (378)
Securities available-for-sale |  | 9,622
Other disclosures |  |
Securities available-for-sale |  | 9,622
Collateralized mortgage obligations |  |
Securities Available-for-Sale |  |
Amortized Cost | 442,987 | 596,336
Gross Unrealized Gains | 421 | 1
Gross Unrealized Losses | (50,864) | (62,569)
Securities available-for-sale | 392,544 | 533,768
Other disclosures |  |
Securities available-for-sale | 392,544 | 533,768
Asset-backed Securities |  |
Securities Available-for-Sale |  |
Amortized Cost | 69,248 | 210,388
Gross Unrealized Gains | 42 | 6
Gross Unrealized Losses | (3,124) | (8,466)
Securities available-for-sale | 66,166 | 201,928
Other disclosures |  |
Securities available-for-sale | 66,166 | 201,928
Collateralized loan obligations. |  |
Securities Available-for-Sale |  |
Amortized Cost | 173,201 | 180,276
Gross Unrealized Gains | 30 |
Gross Unrealized Losses | (1,350) | (5,530)
Securities available-for-sale | 171,881 | 174,746
Other disclosures |  |
Securities available-for-sale | $ 171,881 | $ 174,746
Minimum |  |
Other disclosures |  |
Debt securities, available-for-sale, allowance for credit loss, percent of market value loss | 5.00% |
Debt securities, available-for-sale, allowance for credit loss, market value loss | $ 200,000 |

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