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Borrowings - Additional information (Details) $ in Thousands |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Feb. 24, 2023 USD ($) | Feb. 24, 2020 USD ($) | Dec. 31, 2016 | Jun. 30, 2023 USD ($) | Jun. 30, 2021 USD ($) | Jun. 30, 2024 USD ($) item | Jun. 30, 2023 USD ($) | Dec. 31, 2023 USD ($)
Borrowings |  |  |  |  |  |  |  |
Number of customers having secured balances exceeding specified percentage of stockholders equity | item |  |  |  |  |  | 0 |  |
Threshold percentage of stockholders' equity |  |  |  |  |  | 10.00% |  |
Borrowings at FHLBC as percentage of total assets |  |  |  |  |  | 35.00% |  |
FHLBC stock |  |  |  |  |  | $ 17,100 |  | $ 18,500
Proceeds from term note |  | $ 30,000 |  |  |  |  |  |
Repayment of term note |  |  |  |  |  |  | $ 9,000 |
Basis points added to reference rate (as a percent) |  | 1.75% |  |  |  |  |  |
Outstanding, net of deferred issuance costs |  |  |  |  |  | 59,400 |  | 59,400
Asset Pledged as Collateral with Right | Securities sold under repurchase agreements |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Investment securities pledged with financial institutions, dollars |  |  |  |  |  | 73,600 |  | 45,700
Securities sold under repurchase agreements |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Investment securities pledged with financial institutions, dollars |  |  |  |  |  | $ 46,500 |  | 26,500
Federal Home Loan Bank Advances |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Borrowings at FHLBC as percentage of book value of certain mortgage loans |  |  |  |  |  | 60.00% |  |
FHLBC advance amount |  |  |  |  |  | $ 330,000 |  | $ 405,000
FHLBC stock |  |  |  |  |  | 17,100 |  |
Principal balance of loans collateralized |  |  |  |  |  | 1,380,000 |  |
Combined collateral value |  |  |  |  |  | 933,900,000 |  |
Amount available for additional borrowings |  |  |  |  |  | $ 603,900 |  |
Senior notes |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  | 5.75% |  |  |  |  |
Debt Instrument, Term |  |  | 10 years |  |  |  |  |
Interest rate term |  |  | 5 years |  |  |  |  |
Effective interest rate |  |  |  | 9.39% |  |  | 9.39% |
Debt issuance costs |  |  |  | $ 362 |  |  | $ 362 |
Debt instrument redemption price, percentage |  |  |  | 12.85% |  | 100.00% |  |
Debt redeemed amount |  |  |  | $ 45,000 |  |  | $ 45,000 |
Senior notes | Debt Instrument Variable Rate Base LIBOR |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Basis points added to reference rate (as a percent) |  |  | 3.85% |  |  |  |  |
Term Debt |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Proceeds from term note |  | $ 20,000 |  |  |  |  |  |
Repayment of term note | $ 9,000 |  |  |  |  |  |  |
Debt term |  | 3 years |  |  |  |  |  |
Subordinated Notes Due 2031 |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  | 3.50% |  |  |
Face amount |  |  |  |  | $ 60,000 |  |  |
Subordinated Notes Due 2031 | Three Months Secured Overnight Financing Rate |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |
Basis points added to reference rate (as a percent) |  |  |  |  | 2.73% |  |  |

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- Definition The cash outflow for a borrowing supported by a written promise to pay an obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-15 + Details
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