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Note 10 - Fair Values of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($) | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Securities available for sale |  | $ 506,125,000 | $ 387,347,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 28,900,000 | 24,000,000.0
Reported Value Measurement [Member] |  |  |
Securities available for sale | [1] | 506,125,000 | 387,347,000
FHLBI stock | [2] | 18,002,000 | 18,002,000
Estimate of Fair Value Measurement [Member] |  |  |
Securities available for sale | [1] | 506,125,000 | 387,347,000
FHLBI stock | [2] | 18,002,000 | 18,002,000
Fair Value, Inputs, Level 1 [Member] |  |  |
Securities available for sale |  | 0 | 0
Fair Value, Inputs, Level 1 [Member] | Reported Value Measurement [Member] |  |  |
Cash |  | 17,782,000 | 16,953,000
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Cash |  | 17,782,000 | 16,953,000
Fair Value, Inputs, Level 2 [Member] | Reported Value Measurement [Member] |  |  |
Cash equivalents |  | 741,749,000 | 609,053,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 27,720,000 | 22,888,000
Mortgage servicing rights |  | 10,168,000 | 8,189,000
Accrued interest receivable |  | 9,651,000 | 10,861,000
Deposits |  | 3,671,271,000 | 3,411,553,000
Repurchase agreements |  | 169,737,000 | 118,365,000
FHLBI advances |  | 394,000,000 | 394,000,000
Subordinated debentures |  | 47,904,000 | 47,563,000
Accrued interest payable |  | 1,885,000 | 2,313,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Cash equivalents |  | 741,749,000 | 609,053,000
Mortgages Held-for-sale, Fair Value Disclosure |  | 28,915,000 | 24,029,000
Mortgage servicing rights |  | 13,769,000 | 10,006,000
Accrued interest receivable |  | 9,651,000 | 10,861,000
Deposits |  | 3,656,246,000 | 3,397,768,000
Repurchase agreements |  | 169,737,000 | 118,365,000
FHLBI advances |  | 407,972,000 | 410,881,000
Subordinated debentures |  | 47,859,000 | 47,574,000
Accrued interest payable |  | 1,885,000 | 2,313,000
Fair Value, Inputs, Level 3 [Member] | Reported Value Measurement [Member] |  |  |
Loans, net |  | 3,212,928,000 | 3,155,503,000
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member] |  |  |
Loans, net |  | $ 3,297,771,000 | $ 3,294,522,000
[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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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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