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v3.23.1

Borrowings - Additional information (Details) |  |  | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Feb. 24, 2023 USD ($) | Feb. 24, 2020 USD ($) | Mar. 31, 2023 USD ($) item | Jun. 30, 2022 USD ($) | Mar. 31, 2022 USD ($) | Dec. 31, 2016 | Dec. 31, 2022 USD ($) | Jun. 30, 2021 USD ($) | Apr. 20, 2018 USD ($)
Borrowings |  |  |  |  |  |  |  |  |
Securities available-for-sale, at fair value |  |  | $ 1,455,068,000 |  |  |  | $ 1,539,359,000 |  |
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% |  |  |  |  |  |
Borrowings at FHLBC as percentage of book value of certain mortgage loans |  |  | 60.00% |  |  |  |  |  |
FHLBC stock |  |  | $ 15,300,000 |  |  |  | 5,600,000 |  |
Federal Home Loan Bank Chicago ("FHLBC") and Federal Reserve Bank Chicago ("FRBC") stock |  |  | 30,205,000 |  |  |  | 20,530,000 |  |
Proceeds from term note |  | $ 30,000,000.0 |  |  |  |  |  |  |
Repayment of term note |  |  | 9,000,000 |  | $ 1,000,000 |  |  |  |
Senior notes |  |  | 44,611,000 |  |  |  | 44,585,000 |  |
Basis points added to reference rate (as a percent) |  | 175.00% |  |  |  |  |  |  |
Total borrowings |  |  | 472,599,000 |  |  |  | 260,811,000 |  |
Asset Pledged as Collateral with Right | Securities sold under repurchase agreements |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Investment securities pledged with financial institutions, dollars |  |  |  |  |  |  | 32,200,000 |  |
Securities available-for-sale, at fair value |  |  | $ 65,900,000 |  |  |  | 71,400,000 |  |
GCFC/ABC Bank |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Debt assumed |  |  |  |  |  |  |  |  | $ 23,400,000
Balance of borrowings paid off |  |  |  | $ 5,900,000 |  |  |  |  |
Three Months Secured Overnight Financing Rate |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Basis points added to reference rate (as a percent) |  |  | 273.00% |  |  |  |  |  |
Securities sold under repurchase agreements |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Total borrowings |  |  | $ 27,897,000 |  |  |  | 32,156,000 |  |
Securities sold under repurchase agreements | Asset Pledged as Collateral with Right | Securities sold under repurchase agreements |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Investment securities pledged with financial institutions, dollars |  |  | $ 27,900,000 |  |  |  |  |  |
Federal Home Loan Bank Advances |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Borrowings at FHLBC as percentage of book value of certain mortgage loans |  |  | 60.00% |  |  |  |  |  |
FHLBC advance amount |  |  | $ 315,000,000.0 |  |  |  | 90,000,000.0 |  |
FHLBC stock |  |  | 15,300,000 |  |  |  |  |  |
Principal balance of loans collateralized |  |  | 1,500,000,000 |  |  |  |  |  |
Combined collateral value |  |  | 1,060,000,000.00 |  |  |  |  |  |
Amount available for additional borrowings |  |  | 743,600,000 |  |  |  |  |  |
Subordinated debentures |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Total borrowings |  |  | 59,318,000 |  |  |  | 59,297,000 |  |
Notes Payable to Banks [Member] |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Total borrowings |  |  |  |  |  |  | 9,000,000 |  |
Junior subordinated debentures |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Total borrowings |  |  | 25,773,000 |  |  |  | $ 25,773,000 |  |
Senior Notes [Member] |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  | 5.75% |  |  |
Senior notes |  |  | $ 44,600,000 |  |  |  |  |  |
Debt Instrument, Term |  |  |  |  |  | 10 years |  |  |
Interest rate term |  |  |  |  |  | 5 years |  |  |
Effective interest rate |  |  | 9.01% |  |  |  | 8.62% |  |
Debt issuance costs |  |  | $ 389,000 |  |  |  | $ 415,000 |  |
Amortization period for deferred financing costs |  |  | 10 years |  |  |  |  |  |
Total borrowings |  |  | $ 44,611,000 |  |  |  | 44,585,000 |  |
Debt instrument redemption price, percentage |  |  | 100.00% |  |  |  |  |  |
Senior Notes [Member] | Debt Instrument, Variable Rate Base LIBOR [Member] |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Basis points added to reference rate (as a percent) |  |  |  |  |  | 385.00% |  |  |
Term Debt |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Proceeds from term note |  | $ 20,000,000.0 |  |  |  |  |  |  |
Repayment of term note | $ 9,000,000.0 |  |  |  |  |  |  |  |
Debt term |  | 3 years |  |  |  |  |  |  |
Subordinated Notes Due 2031 |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  | 3.50% |  |  |  |  | 3.50% |
Outstanding, net of deferred issuance costs |  |  | $ 59,300,000 |  |  |  | $ 59,300,000 |  |
Face amount |  |  |  |  |  |  |  | $ 60,000,000.0 |

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