Note 6 - Loans Held for Investment (Details) - Non-Accrual Loans (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	$ 2,016	$ 1,798
Performing TDRs:
Total TDR loans accounted for on a non-accrual status	4,416	5,038
Total non-accrual loans	4,416	5,038
Percentage of total loans held for investment, net	0.90%	1.10%
Loans over 90 days past due and still accruing		389
Other real estate owned	7,082	7,756
Total non-performing assets	11,498fsbk_TotalNonperformingAssets	13,183fsbk_TotalNonperformingAssets
Commercial Real Estate Loans [Member] \| Total Non-Accrual Loans [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	1,155	1,182
Commercial Real Estate Loans [Member]
Performing TDRs:
Performing TDRs on non-accrual status	123	127
Consumer Real Estate Loans [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	51	51
Past-due TDRs [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	1,206	1,233
Residential Real Estate Loans [Member]
Performing TDRs:
Performing TDRs on non-accrual status	827	834
Commercial Lots and Raw Land [Member]
Performing TDRs:
Performing TDRs on non-accrual status	244	1,046
Total Non-Accrual Loans [Member]
Performing TDRs:
Performing TDRs on non-accrual status	1,194	2,007
Total TDR loans accounted for on a non-accrual status	2,400	3,240
Total non-accrual loans	2,400	3,240
Residential Real Estate Loans [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	842	727
Performing TDRs:
Loans over 90 days past due and still accruing		389
Residential Lots and Raw Land [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	10	11
Commercial Real Estate Loans [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	529	554
Commercial Lots and Raw Land [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	39	32
Lease Receivables [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	146	69
Consumer Real Estate Loans [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	295	214
Consumer Lots and Raw Land [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	76	124
Home Equity Lines of Credit [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	73	61
Consumer Other [Member]
Non-TDR loans accounted for on a non-accrual status:
Nonperforming loans on a non-accrual status	$ 6	$ 6

Reflects the carrying amount of loans deemed to be performing on which no interest is continuing to be recognized.

No definition available.

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- Definition

Value of non-performing assets.

+ References

No definition available.

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- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

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- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

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- Definition

Reflects the percentage derived from dividing impaired loans on which interest has ceased to be accrued by total loans.

+ References

No definition available.

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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