XML 88 R102.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Related Party Transactions (Details) - Directors Affiliates and Executive Officers [Member] - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Summary of loan transactions with directors, including their affiliates and executive officers |  |
Balance, beginning of year | $ 13,969 | $ 15,276
New loans | 6,709 | 5,686
Less loan payments | (9,787) | (6,993)
Balance, end of year | $ 10,891 | $ 13,969

X
- Definition Loan payments by related party. + References No definition available. + Details
Name: | sfst_LoanPaymentsRelatedParty
Namespace Prefix: | sfst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Loan transactions with related party. + References No definition available. + Details
Name: | sfst_LoanTransactionsWithRelatedParty
Namespace Prefix: | sfst_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition New loans. + References No definition available. + Details
Name: | sfst_NewLoans
Namespace Prefix: | sfst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=sfst_DirectorsAffiliatesAndExecutiveOfficersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |