XML 77 R56.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Investment Securities (Details 2) $ in Thousands | Dec. 31, 2019 USD ($) Investments | Dec. 31, 2018 USD ($) Investments
--- | --- | ---
Summary of gross unrealized losses on investment securities and fair market value of related securities |  |
Number of investments, Less than 12 months | Investments | 28 | 8
Available-for-sale Securities, Less than 12 months, Fair Value | $ 30,095 | $ 11,746
Available-for-sale Securities, Less than 12 months, Unrealized losses | $ 168 | $ 64
Number of investments, 12 months or longer | Investments | 22 | 53
Available-for-sale Securities, 12 months or longer, Fair Value | $ 20,296 | $ 46,524
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 265 | $ 1,270
Number of investments, Total | Investments | 50 | 61
Available-for-sale Securities, Fair Value, Total | $ 50,391 | $ 58,270
Available-for-sale Securities, Unrealized Losses, Total | $ 433 | $ 1,334
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 | Investments | 1 | 1
Available-for-sale Securities, Less than 12 months, Fair Value | $ 499 | $ 1,246
Available-for-sale Securities, Less than 12 months, Unrealized losses | 1 | $ 3
Number of investments, 12 months or longer | Investments |  | 8
Available-for-sale Securities, 12 months or longer, Fair Value |  | $ 7,035
Available-for-sale Securities, 12 months or Longer, Unrealized losses |  | $ 191
Number of investments, Total | Investments | 1 | 9
Available-for-sale Securities, Fair Value, Total | $ 499 | $ 8,281
Available-for-sale Securities, Unrealized Losses, Total | $ 1 | $ 194
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 | Investments |  |
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 | Investments | 1 | 2
Available-for-sale Securities, 12 months or longer, Fair Value | $ 531 | $ 3,525
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 19 | $ 103
Number of investments, Total | Investments | 1 | 2
Available-for-sale Securities, Fair Value, Total | $ 531 | $ 3,525
Available-for-sale Securities, Unrealized Losses, Total | $ 19 | $ 103
State 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 | Investments | 2 |
Available-for-sale Securities, Less than 12 months, Fair Value | $ 2,093 |
Available-for-sale Securities, Less than 12 months, Unrealized losses | 24 |
Number of investments, 12 months or longer | Investments |  | 7
Available-for-sale Securities, 12 months or longer, Fair Value |  | $ 2,829
Available-for-sale Securities, 12 months or Longer, Unrealized losses |  | $ 63
Number of investments, Total | Investments | 2 | 7
Available-for-sale Securities, Fair Value, Total | $ 2,093 | $ 2,829
Available-for-sale Securities, Unrealized Losses, Total | $ 24 | $ 63
Asset-backed Securities [Member] |  |
Summary of gross unrealized losses on investment securities and fair market value of related securities |  |
Number of investments, Less than 12 months | Investments | 5 | 4
Available-for-sale Securities, Less than 12 months, Fair Value | $ 5,921 | $ 6,707
Available-for-sale Securities, Less than 12 months, Unrealized losses | $ 68 | $ 49
Number of investments, 12 months or longer | Investments | 5 |
Available-for-sale Securities, 12 months or longer, Fair Value | $ 7,246 |
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 116 |
Number of investments, Total | Investments | 10 | 4
Available-for-sale Securities, Fair Value, Total | $ 13,167 | $ 6,707
Available-for-sale Securities, Unrealized Losses, Total | $ 184 | $ 49
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 | Investments | 4 |
Available-for-sale Securities, Less than 12 months, Fair Value | $ 3,842 |
Available-for-sale Securities, Less than 12 months, Unrealized losses | $ 2 |
Number of investments, 12 months or longer | Investments | 4 | 10
Available-for-sale Securities, 12 months or longer, Fair Value | $ 2,323 | $ 7,402
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 13 | $ 242
Number of investments, Total | Investments | 8 | 10
Available-for-sale Securities, Fair Value, Total | $ 6,165 | $ 7,402
Available-for-sale Securities, Unrealized Losses, Total | $ 15 | $ 242
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 | Investments | 14 | 2
Available-for-sale Securities, Less than 12 months, Fair Value | $ 15,500 | $ 2,689
Available-for-sale Securities, Less than 12 months, Unrealized losses | $ 67 | $ 6
Number of investments, 12 months or longer | Investments | 11 | 23
Available-for-sale Securities, 12 months or longer, Fair Value | $ 9,462 | $ 22,814
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 102 | $ 545
Number of investments, Total | Investments | 25 | 25
Available-for-sale Securities, Fair Value, Total | $ 24,962 | $ 25,503
Available-for-sale Securities, Unrealized Losses, Total | $ 169 | $ 551
Mortgage-backed securities [Member] | GNMA [Member] |  |
Summary of gross unrealized losses on investment securities and fair market value of related securities |  |
Number of investments, Less than 12 months | Investments | 2 | 1
Available-for-sale Securities, Less than 12 months, Fair Value | $ 2,240 | $ 1,104
Available-for-sale Securities, Less than 12 months, Unrealized losses | $ 6 | $ 6
Number of investments, 12 months or longer | Investments | 1 | 3
Available-for-sale Securities, 12 months or longer, Fair Value | $ 734 | $ 2,919
Available-for-sale Securities, 12 months or Longer, Unrealized losses | $ 15 | $ 126
Number of investments, Total | Investments | 3 | 4
Available-for-sale Securities, Fair Value, Total | $ 2,974 | $ 4,023
Available-for-sale Securities, Unrealized Losses, Total | $ 21 | $ 132

X
- Definition Number of investments in continuous unrealized loss position. + References No definition available. + Details
Name: | sfst_NumberOfInvestmentsInContinuousUnrealizedLossPosition
Namespace Prefix: | sfst_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- 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

X
- 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

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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 No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 twelve months or longer. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AgencySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=sfst_SbaSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |