Description of present value of cash flow of modified FHLB advances.

No definition available.

Name:	sfst_DescriptionOfPresentValueOfCashFlowOfModifiedFhlbAdvances
Namespace Prefix:	sfst_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	sfst_FederalHomeLoanBankAdvancesAndOtherBorrowingsTextualAbstract
Namespace Prefix:	sfst_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

FHLB advances and related debt.

+ References

No definition available.

+ Details

Name:	sfst_FhlbAdvancesAndRelatedDebt
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

FHLB advances weighted average remaining life.

+ References

No definition available.

+ Details

Name:	sfst_FhlbAdvancesWeightedAverageRemainingLife
Namespace Prefix:	sfst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans maturing after one year with fixed interest rates.

+ References

No definition available.

+ Details

Name:	sfst_LoansMaturingAfterOneYearWithFixedInterestRates
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Mortgage loan pledged as collateral for advances from FHLB.

+ References

No definition available.

+ Details

Name:	sfst_MortgageLoanPledgedAsCollateralForAdvancesFromFhlb
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of restructured FHLB advances.

+ References

No definition available.

+ Details

Name:	sfst_NumberOfRestructuredFhlbAdvances
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of structured debt agreements.

+ References

No definition available.

+ Details

Name:	sfst_NumberOfStructuredDebtAgreements
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Restructured FHLB advances.

+ References

No definition available.

+ Details

Name:	sfst_RestructuredFhlbAdvances
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Restructured FHLB advances weighted average interest rate.

+ References

No definition available.

+ Details

Name:	sfst_RestructuredFhlbAdvancesWeightedAverageInterestRate
Namespace Prefix:	sfst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Restructured FHLB advances weighted average remaining life.

+ References

No definition available.

+ Details

Name:	sfst_RestructuredFhlbAdvancesWeightedAverageRemainingLife
Namespace Prefix:	sfst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Structured debt agreements secured by investment securities.

+ References

No definition available.

+ Details

Name:	sfst_StructuredDebtAgreementsSecuredByInvestmentSecurities
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

+ References

+ Details

Name:	us-gaap_AdvancesFromFederalHomeLoanBanks
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Describes the weighted average interest rate applicable to the specific advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

+ References

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 (b)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Federal Home Loan Bank (FHLB) advances which have fixed interest.

+ References

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 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFixedRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of Federal Home Loan Bank (FHLB) advances which have floating interest rates.

+ References

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 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13, 16

-Article 9

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryByInterestRateTypeFloatingRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 325

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6478792&loc=d3e63345-112809

+ Details

Name:	us-gaap_FederalHomeLoanBankStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Line-of-Credit Arrangement

-URI http://asc.fasb.org/extlink&oid=6517033

+ Details

Name:	us-gaap_LinesOfCreditCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(1))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph 1

-Article 9

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=45278096&loc=d3e9760-107771

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(1)(a)(i))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_SecuritiesSoldUnderAgreementsToRepurchase
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=sfst_InterestRateCeilingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateFloorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Federal Home Loan Bank Advances and Other Borrowings (Details Textual) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014 Agreement	Dec. 31, 2014 Agreement	Dec. 31, 2013 Agreement	Jul. 25, 2012
Federal Home Loan Bank Advances and Other Borrowings (Textual)
FHLB advances and related debt		$ 135,200,000sfst_FhlbAdvancesAndRelatedDebt	$ 124,100,000sfst_FhlbAdvancesAndRelatedDebt
FHLB advances		116,000,000	103,500,000
Securities sold under structured agreements to repurchase		19,200,000	19,200,000
Line of credit			1,400,000us-gaap_LinesOfCreditCurrent
Mortgage loan pledged as collateral for advances from FHLB		241,100,000
FHLB stock		6,000,000us-gaap_FederalHomeLoanBankStock	5,600,000us-gaap_FederalHomeLoanBankStock
Number of restructured FHLB advances	5sfst_NumberOfRestructuredFhlbAdvances		1sfst_NumberOfRestructuredFhlbAdvances
Restructured FHLB advances	59,500,000sfst_RestructuredFhlbAdvances		5,000,000sfst_RestructuredFhlbAdvances
Description of present value of cash flow of modified FHLB advances		Present value of the cash flows of the modified advance will not change by more than 10% from the present value of the cash flows of the original advances.
FHLB advances, weighted average rate		2.31%	4.07%
FHLB advances, weighted average remaining life		40 months	45 months
Restructured FHLB advances, weighted average interest rate		2.22%	3.05%
Restructured FHLB advances, weighted average remaining life		43 months	60 months
Structured debt agreements secured by investment securities		21,800,000	21,800,000
Number of structured debt agreements		4sfst_NumberOfStructuredDebtAgreements	4sfst_NumberOfStructuredDebtAgreements
Interest only line of credit		10,000,000
Interest only line of credit, outstanding amount				1,500,000us-gaap_LineOfCredit
Line of credit, interest rate			5.00%
Line of credit facility, maturity date		Jun. 06, 2017
Loans maturing after one year with fixed interest rates			51,500,000
FHLB advances at floating rates		64,500,000
FHLB advances at fixed rates		$ 51,500,000
LIBOR [Member]
Federal Home Loan Bank Advances and Other Borrowings (Textual)
Line of credit facility, Interest rate description		LIBOR plus 2.90%
Floor [Member]
Federal Home Loan Bank Advances and Other Borrowings (Textual)
Line of credit, interest rate		3.25%
Ceiling [Member]
Federal Home Loan Bank Advances and Other Borrowings (Textual)
Line of credit, interest rate		5.15%