Note 8 - Deposits (Details Textual) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Time Deposits, at or Above FDIC Insurance Limit	$ 364,329,340	$ 300,852,485
Federal Home Loan Bank of Des Moines [Member]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	35,000,000	40,000,000
Letters of Credit Outstanding, Amount		0	$ 0
Federal Home Loan Bank of Chicago [Member]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	10,100,000	7,000,000
Letters of Credit Outstanding, Amount	$ 0	$ 0

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

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Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818

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