XML 40 R29.htm IDEA: XBRL DOCUMENT
v3.21.1

Investment Securities (Schedule of Amortized Costs and Fair Value of Investment Securities) (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | $ 92,997 | $ 94,729
Total investment securities available for sale, Gross Unrealized Gains | 1,136 | 1,586
Total investment securities available for sale, Gross Unrealized Losses | 1,250 | 291
Total investment securities available for sale, Amortized Cost | 93,111 | 93,434
US Government Agencies [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 7,263 | 6,493
Total investment securities available for sale, Gross Unrealized Gains | 1 | 1
Total investment securities available for sale, Gross Unrealized Losses | 232 | 8
Total investment securities available for sale, Amortized Cost | 7,494 | 6,500
SBA Securities [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 480 | 485
Total investment securities available for sale, Gross Unrealized Gains |  |
Total investment securities available for sale, Gross Unrealized Losses | 18 | 19
Total investment securities available for sale, Amortized Cost | 498 | 504
State and Political Subdivisions [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 19,811 | 19,388
Total investment securities available for sale, Gross Unrealized Gains | 451 | 804
Total investment securities available for sale, Gross Unrealized Losses | 272 | 30
Total investment securities available for sale, Amortized Cost | 19,632 | 18,614
Asset-backed Securities [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 11,283 | 11,529
Total investment securities available for sale, Gross Unrealized Gains | 58 | 15
Total investment securities available for sale, Gross Unrealized Losses | 9 | 73
Total investment securities available for sale, Amortized Cost | 11,234 | 11,587
Mortgage Backed Securities [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 54,160 | 56,834
Total investment securities available for sale, Gross Unrealized Gains | 626 | 766
Total investment securities available for sale, Gross Unrealized Losses | 719 | 161
Total investment securities available for sale, Amortized Cost | 54,253 | 56,229
Mortgage Backed Securities [Member] | FHLMC [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 13,012 | 12,316
Total investment securities available for sale, Gross Unrealized Gains | 167 | 206
Total investment securities available for sale, Gross Unrealized Losses | 254 | 47
Total investment securities available for sale, Amortized Cost | 13,099 | 12,157
Mortgage Backed Securities [Member] | FNMA [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 33,917 | 36,309
Total investment securities available for sale, Gross Unrealized Gains | 424 | 507
Total investment securities available for sale, Gross Unrealized Losses | 377 | 91
Total investment securities available for sale, Amortized Cost | 33,870 | 35,893
Mortgage Backed Securities [Member] | GNMA [Member] |  |
Available for sale |  |
Available-for-sale securities, investment securities, Fair Value | 7,231 | 8,209
Total investment securities available for sale, Gross Unrealized Gains | 35 | 53
Total investment securities available for sale, Gross Unrealized Losses | 88 | 23
Total investment securities available for sale, Amortized Cost | $ 7,284 | $ 8,179

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

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
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: |