Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Financial assets:
Cash and due from banks	$ 28,898	$ 38,599
Interest bearing deposits with financial institutions	11,438	16,636
Securities available-for-sale	509,090	541,248	$ 509,090
FHLBC and FRBC Stock	11,179	13,433
Bank-owned life insurance	62,002	61,544
Financial liabilities:
Noninterest bearing deposits	629,909	618,830
Other short-term borrowings	85,000	149,500
Junior subordinated debentures	57,698	57,686
Reported Value Measurement [Member]
Financial assets:
Cash and due from banks	28,898	38,599
Interest bearing deposits with financial institutions	11,438	16,636
Securities available-for-sale	509,090	541,248
FHLBC and FRBC Stock	11,179	13,433
Loans held for sale	2,134	2,984
Net loans	1,883,830	1,878,021
Accrued interest receivable	11,083	10,940
Financial liabilities:
Noninterest bearing deposits	629,909	618,830
Interest bearing deposits	1,493,603	1,497,843
Securities sold under repurchase agreements	42,361	46,632
Other short-term borrowings	85,000	149,500
Junior subordinated debentures	57,698	57,686
Senior notes	44,183	44,158
Note payable and other borrowings	13,207	15,379
Interest rate swap	1,131	58
Borrowing interest payable	764	281
Deposit interest payable	963	973
Estimate of Fair Value Measurement [Member]
Financial assets:
Cash and due from banks	28,898	38,599
Interest bearing deposits with financial institutions	11,438	16,636
Securities available-for-sale	509,090	541,248
FHLBC and FRBC Stock	11,179	13,433
Loans held for sale	2,134	2,984
Net loans	1,893,690	1,867,594
Accrued interest receivable	11,083	10,940
Financial liabilities:
Noninterest bearing deposits	629,909	618,830
Interest bearing deposits	1,491,384	1,495,614
Securities sold under repurchase agreements	42,361	46,632
Other short-term borrowings	85,000	149,500
Junior subordinated debentures	43,284	47,625
Senior notes	45,551	45,008
Note payable and other borrowings	13,207	15,379
Interest rate swap	1,131	58
Borrowing interest payable	764	281
Deposit interest payable	963	973
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and due from banks	28,898	38,599
Interest bearing deposits with financial institutions	11,438	16,636
Securities available-for-sale	3,960	3,923
Financial liabilities:
Noninterest bearing deposits	629,909	618,830
Junior subordinated debentures	34,044	32,989
Senior notes	45,551	45,008
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Securities available-for-sale	485,574	529,160
FHLBC and FRBC Stock	11,179	13,433
Loans held for sale	2,134	2,984
Accrued interest receivable	11,083	10,940
Financial liabilities:
Interest bearing deposits	1,491,384	1,495,614
Securities sold under repurchase agreements	42,361	46,632
Other short-term borrowings	85,000	149,500
Junior subordinated debentures	9,240	14,636
Note payable and other borrowings	13,207	15,379
Interest rate swap	1,131	58
Borrowing interest payable	764	281
Deposit interest payable	963	973
Fair Value, Inputs, Level 3 [Member]
Financial assets:
Securities available-for-sale	19,556	8,165	$ 26,500
Net loans	$ 1,893,690	$ 1,867,594

Represents the fair value of interest payable related to deposits at the balance sheet date.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.

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The aggregate of all domestic and foreign interest-bearing deposit liabilities.

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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