Note 15 - Regulatory Capital Requirements (Details) - The Bank's Actual Regulatory Capital Amounts and Ratios (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
The Bank's Actual Regulatory Capital Amounts and Ratios [Abstract]
Total Risk-Based Capital Ratio (to Risk Weighted Assets)	$ 85,099us-gaap_Capital	$ 82,670us-gaap_Capital
Total Risk-Based Capital Ratio (to Risk Weighted Assets)	15.20%us-gaap_CapitalToRiskWeightedAssets	14.60%us-gaap_CapitalToRiskWeightedAssets
Common Equity Tier 1 Risk-Based Capital Ratio (to Risk Weighted Assets)	78,110fsbk_CommonEquityTier1RiskBasedCapital
Common Equity Tier 1 Risk-Based Capital Ratio (to Risk Weighted Assets)	14.00%
Tier 1 Risk-Based Capital Ratio (to Risk Weighted Assets)	78,110us-gaap_TierOneRiskBasedCapital	75,568us-gaap_TierOneRiskBasedCapital
Tier 1 Risk-Based Capital Ratio (to Risk Weighted Assets)	14.00%	13.30%
Tier 1 Leverage Capital Ratio (to Average Assets)	$ 78,110us-gaap_TierOneLeverageCapital	$ 75,568us-gaap_TierOneLeverageCapital
Tier 1 Leverage Capital Ratio (to Average Assets)	9.00%	9.70%

The amount of common equity tier 1 capital as defined in the regulations.

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Total common equity tier 1 capital divided by risk weighted assets as defined in the regulations.

+ References

No definition available.

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The amount of total capital as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

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-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 3

-Subparagraph (c)(1)

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- Definition

Total Capital divided by risk weighted assets as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1H

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Subparagraph (c)(1)

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- Definition

Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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- Definition

Tier 1 Risk Based Capital as defined in the regulations.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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