Investment Securities (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Investment	Dec. 31, 2013 Investment
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months	3	35
Available-for-sale Securities, Less than 12 months, Fair Value	$ 4,407	$ 32,383
Available-for-sale Securities, Less than 12 Months, Unrealized losses	11	1,914
Number of investments, 12 months or longer	13	11
Available-for-sale Securities, 12 months or longer, Fair Value	20,967	8,976
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	479	706
Number of investments, Total	16	46
Available-for-sale Securities, Fair Value, Total	25,374	41,359
Available-for-sale Securities, Unrealized Losses, Total	490	2,620
US government agencies [Member]
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months		3
Available-for-sale Securities, Less than 12 months, Fair Value		7,755
Available-for-sale Securities, Less than 12 Months, Unrealized losses		1,001
Number of investments, 12 months or longer	2
Available-for-sale Securities, 12 months or longer, Fair Value	7,569
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	215
Number of investments, Total	2	3
Available-for-sale Securities, Fair Value, Total	7,569	7,755
Available-for-sale Securities, Unrealized Losses, Total	215	1,001
SBA securities [Member]
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months
Available-for-sale Securities, Less than 12 months, Fair Value
Available-for-sale Securities, Less than 12 Months, Unrealized losses
Number of investments, 12 months or longer	2	2
Available-for-sale Securities, 12 months or longer, Fair Value	5,154	5,271
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	182	487
Number of investments, Total	2	2
Available-for-sale Securities, Fair Value, Total	5,154	5,271
Available-for-sale Securities, Unrealized Losses, Total	182	487
States and political subdivisions [Member]
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months		22
Available-for-sale Securities, Less than 12 months, Fair Value		8,482
Available-for-sale Securities, Less than 12 Months, Unrealized losses		364
Number of investments, 12 months or longer	7	9
Available-for-sale Securities, 12 months or longer, Fair Value	3,488	3,705
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	51	219
Number of investments, Total	7	31
Available-for-sale Securities, Fair Value, Total	3,488	12,187
Available-for-sale Securities, Unrealized Losses, Total	51	583
Mortgage Backed Securities [Member] \| FHLMC [Member]
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months	1	3
Available-for-sale Securities, Less than 12 months, Fair Value	731	5,006
Available-for-sale Securities, Less than 12 Months, Unrealized losses	1	186
Number of investments, 12 months or longer	1
Available-for-sale Securities, 12 months or longer, Fair Value	2,472
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	11
Number of investments, Total	2	3
Available-for-sale Securities, Fair Value, Total	3,203	5,006
Available-for-sale Securities, Unrealized Losses, Total	12	186
Mortgage Backed Securities [Member] \| FNMA [Member]
Summary of gross unrealized losses on investment securities and fair market value of related securities
Number of investments, Less than 12 months	2	7
Available-for-sale Securities, Less than 12 months, Fair Value	3,676	11,140
Available-for-sale Securities, Less than 12 Months, Unrealized losses	10	363
Number of investments, 12 months or longer	1
Available-for-sale Securities, 12 months or longer, Fair Value	2,284
Available-for-sale Securities, 12 Months or Longer, Unrealized losses	20
Number of investments, Total	3	7
Available-for-sale Securities, Fair Value, Total	5,960	11,140
Available-for-sale Securities, Unrealized Losses, Total	$ 30	$ 363

Number of investments in continuous unrealized loss position.

No definition available.

Name:	sfst_NumberOfInvestmentsInContinuousUnrealizedLossPosition
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of investments in continuous unrealized loss position, less than twelve months.

+ References

No definition available.

+ Details

Name:	sfst_NumberOfInvestmentsInContinuousUnrealizedLossPositionLessThanTwelveMonths
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of investments in continuous unrealized loss position twelve months or longer.

+ References

No definition available.

+ Details

Name:	sfst_NumberOfInvestmentsInContinuousUnrealizedLossPositionTwelveMonthsOrLonger
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Definition

Amount of unrealized loss on securities classified as available-for-sale.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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

- Definition

Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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

- Definition

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=sfst_SbaSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AgencySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: