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Note 10 - Fair Values of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($) | Mar. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Securities available for sale |  | $ 605,661,000 | $ 592,743,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 15,200,000 | 16,700,000
Reported Value Measurement [Member] |  |  |
Securities available for sale | [1] | 605,661,000 | 592,743,000
FHLBI stock | [2] | 17,721,000 | 18,002,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 14,746,000 | 16,117,000
Estimate of Fair Value Measurement [Member] |  |  |
Securities available for sale | [1] | 605,661,000 | 592,743,000
FHLBI stock | [2] | 17,721,000 | 18,002,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 15,208,000 | 16,707,000
Fair Value, Inputs, Level 1 [Member] |  |  |
Securities available for sale |  | 0 | 0
Fair Value, Inputs, Level 1 [Member] | Reported Value Measurement [Member] |  |  |
Cash |  | 18,898,000 | 17,872,000
Cash equivalents |  | 751,306,000 | 957,288,000
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Cash |  | 18,898,000 | 17,872,000
Cash equivalents |  | 751,306,000 | 957,288,000
Fair Value, Inputs, Level 3 [Member] | Reported Value Measurement [Member] |  |  |
Loans, net |  | 3,520,637,000 | 3,418,096,000
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Loans, net |  | 3,542,217,000 | 3,498,345,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member] |  |  |
Mortgage servicing rights |  | 12,484,000 | 12,248,000
Accrued interest receivable |  | 10,655,000 | 9,311,000
Deposits |  | 3,976,251,000 | 4,083,193,000
Repurchase agreements |  | 204,271,000 | 197,463,000
FHLBI advances |  | 382,263,000 | 374,000,000
Accrued interest payable |  | 2,150,000 | 1,393,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member] | Subordinated Debentures [Member] |  |  |
Subordinated debt |  | 48,415,000 | 48,244,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member] | Subordinated Notes [Member] |  |  |
Subordinated debt |  | 88,428,000 | 73,646,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member] | Interest Rate Swap [Member] |  |  |
Interest rate swaps |  | 10,053,000 | 4,609,000
Interest rate swaps |  | 10,246,000 | 4,857,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Mortgage servicing rights |  | 16,533,000 | 15,445,000
Accrued interest receivable |  | 10,655,000 | 9,311,000
Deposits |  | 3,795,104,000 | 4,028,249,000
Repurchase agreements |  | 204,271,000 | 197,463,000
FHLBI advances |  | 372,887,000 | 384,927,000
Accrued interest payable |  | 2,150,000 | 1,393,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] | Subordinated Debentures [Member] |  |  |
Subordinated debt |  | 49,990,000 | 48,284,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] | Subordinated Notes [Member] |  |  |
Subordinated debt |  | 88,429,000 | 73,646,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] |  |  |
Interest rate swaps |  | 10,053,000 | 4,609,000
Interest rate swaps |  | $ 10,246,000 | $ 4,857,000
[1] | See Note 11 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.
[2] | It is not practical to determine the fair value of FHLBI stock due to transferability restrictions; therefore, fair value is estimated at carrying amount.

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