Note 5 - Fair Value of Financial Instruments - Estimated Fair Value of Company's Financial Instruments (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Financial assets:
Securities available for sale	$ 81,174,000	$ 77,472,000
Loans receivable, net	591,840,000	585,931,000
Reported Value Measurement [Member]
Financial assets:
Cash and cash equivalents	26,576,000	37,564,000
Securities available for sale	81,174,000	77,472,000
Loans held for sale	2,234,000	1,837,000
Loans receivable, net	591,840,000	585,931,000
Federal Home Loan Bank stock	867,000	817,000
Accrued interest receivable	2,104,000	2,344,000
Financial liabilities:
Deposits	633,805,000	635,601,000
Accrued interest payable	197,000	146,000
Off-balance sheet financial instruments:
Commitments to extend credit	63,000	28,000
Commitments to sell loans	(12,000)	(11,000)
Estimate of Fair Value Measurement [Member]
Financial assets:
Cash and cash equivalents	26,576,000	37,564,000
Securities available for sale	81,174,000	77,472,000
Loans held for sale	2,234,000	1,837,000
Loans receivable, net	591,626,000	585,494,000
Federal Home Loan Bank stock	867,000	817,000
Accrued interest receivable	2,104,000	2,344
Financial liabilities:
Deposits	628,252,000	635,905,000
Accrued interest payable	197,000	146,000
Off-balance sheet financial instruments:
Commitments to extend credit	63,000	28,000
Commitments to sell loans	(12,000)	(11,000)
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	26,576,000	37,564,000
Securities available for sale
Loans held for sale
Loans receivable, net
Federal Home Loan Bank stock
Accrued interest receivable
Financial liabilities:
Deposits
Accrued interest payable
Off-balance sheet financial instruments:
Commitments to extend credit
Commitments to sell loans
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial assets:
Cash and cash equivalents
Securities available for sale	81,174,000	77,472,000
Loans held for sale	2,234,000	1,837,000
Loans receivable, net	591,626,000	585,494,000
Federal Home Loan Bank stock	867,000	817,000
Accrued interest receivable	2,104,000	2,344,000
Financial liabilities:
Deposits	628,252,000	635,905,000
Accrued interest payable	197,000	146,000
Off-balance sheet financial instruments:
Commitments to extend credit
Commitments to sell loans
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial assets:
Cash and cash equivalents
Securities available for sale
Loans held for sale
Loans receivable, net
Federal Home Loan Bank stock
Accrued interest receivable
Financial liabilities:
Deposits
Accrued interest payable
Off-balance sheet financial instruments:
Commitments to extend credit
Commitments to sell loans
Portion at Other than Fair Value Measurement [Member]
Financial assets:
Cash and cash equivalents
Securities available for sale
Loans held for sale
Loans receivable, net
Federal Home Loan Bank stock
Accrued interest receivable
Financial liabilities:
Deposits
Accrued interest payable
Off-balance sheet financial instruments:
Commitments to extend credit	229,740,000	173,645,000
Commitments to sell loans	$ 10,682,000	$ 5,629,000

Fair value portion of accrued interest payable.

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+ References

No definition available.

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The face amount of financial liabilities related to commitments to sell, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

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- References

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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 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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-Topic 320
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

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The face amount of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

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- Definition

Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

+ References

No definition available.

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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