XML 46 R35.htm IDEA: XBRL DOCUMENT v3.25.3

Loans and Allowance for Credit Losses (Details) - Schedule of classified by credit quality indicators by year of origination - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	$ 361,397	$ 272,703
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	266,241	345,047
Loan balance classified by credit quality indicators, two years before latest fiscal year	313,802	992,601
Loan balance classified by credit quality indicators, three years before latest fiscal year	917,754	620,632
Loan balance classified by credit quality indicators, four years before latest fiscal year	582,821	362,685
Prior	857,109	594,934
Revolving	488,183	441,309
Revolving Converted to Term	1,714	1,856
Total	3,789,021	3,631,767
Current period gross write-offs 2025	(30)
Current period gross write-offs 2024
Current period gross write-offs 2023
Current period gross write-offs 2022
Current period gross write-offs 2021	(21)	(143)
Current period gross write-offs Prior	(78)	(1,085)
Current period gross write-offs Revolving	(72)	(159)
Current period gross write-offs Revolving Converted to Term
Current period gross write-offs Total	(201)	(1,734)
Current period gross write-offs 2020		(347)
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	224,929	182,081
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	194,081	191,539
Loan balance classified by credit quality indicators, two years before latest fiscal year	173,556	689,752
Loan balance classified by credit quality indicators, three years before latest fiscal year	641,713	343,229
Loan balance classified by credit quality indicators, four years before latest fiscal year	319,551	193,677
Prior	553,111	427,039
Revolving	216,371	206,112
Revolving Converted to Term	1,714	1,856
Total	2,325,026	2,235,285
Commercial [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	14,053	24,076
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	20,451	28,921
Loan balance classified by credit quality indicators, two years before latest fiscal year	12,004	35,207
Loan balance classified by credit quality indicators, three years before latest fiscal year	23,181	15,000
Loan balance classified by credit quality indicators, four years before latest fiscal year	2,239
Prior
Revolving
Revolving Converted to Term
Total	71,928	103,204
Commercial [Member] | Business [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	86,893	55,502
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	47,720	41,970
Loan balance classified by credit quality indicators, two years before latest fiscal year	49,285	135,608
Loan balance classified by credit quality indicators, three years before latest fiscal year	111,278	40,486
Loan balance classified by credit quality indicators, four years before latest fiscal year	32,267	17,589
Prior	59,906	57,972
Revolving	215,815	205,592
Revolving Converted to Term	1,247	1,398
Total	604,411	556,117
Current period gross write-offs 2025
Current period gross write-offs 2024
Current period gross write-offs 2023
Current period gross write-offs 2022
Current period gross write-offs 2021		(143)
Current period gross write-offs Prior	(78)	(18)
Current period gross write-offs Revolving	(63)	(72)
Current period gross write-offs Revolving Converted to Term
Current period gross write-offs Total	(141)	(580)
Current period gross write-offs 2020		(347)
Commercial [Member] | Pass [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	14,053	24,076
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	20,451	26,501
Loan balance classified by credit quality indicators, two years before latest fiscal year	12,004	34,067
Loan balance classified by credit quality indicators, three years before latest fiscal year	22,011	15,000
Loan balance classified by credit quality indicators, four years before latest fiscal year	58
Prior
Revolving
Revolving Converted to Term
Total	68,577	99,644
Commercial [Member] | Pass [Member] | Business [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	85,947	54,814
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	46,287	41,743
Loan balance classified by credit quality indicators, two years before latest fiscal year	47,430	129,450
Loan balance classified by credit quality indicators, three years before latest fiscal year	107,471	38,312
Loan balance classified by credit quality indicators, four years before latest fiscal year	30,003	15,716
Prior	55,049	51,566
Revolving	204,217	196,246
Revolving Converted to Term	474	803
Total	576,878	528,650
Commercial [Member] | Watch [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year		2,420
Loan balance classified by credit quality indicators, two years before latest fiscal year		1,140
Loan balance classified by credit quality indicators, three years before latest fiscal year	1,170
Loan balance classified by credit quality indicators, four years before latest fiscal year	2,181
Prior
Revolving
Revolving Converted to Term
Total	3,351	3,560
Commercial [Member] | Watch [Member] | Business [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	704
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	778	132
Loan balance classified by credit quality indicators, two years before latest fiscal year	1,220	5,353
Loan balance classified by credit quality indicators, three years before latest fiscal year	3,177	2,174
Loan balance classified by credit quality indicators, four years before latest fiscal year	2,264	1,423
Prior	4,194	5,243
Revolving	10,971	8,776
Revolving Converted to Term	387	389
Total	23,695	23,490
Commercial [Member] | Special Mention [Member] | Business [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	77	660
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	655	95
Loan balance classified by credit quality indicators, two years before latest fiscal year	635	805
Loan balance classified by credit quality indicators, three years before latest fiscal year	630
Loan balance classified by credit quality indicators, four years before latest fiscal year		65
Prior	589	533
Revolving	160
Revolving Converted to Term	386	206
Total	3,132	2,364
Commercial [Member] | Substandard [Member] | Business [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	165	28
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year		385
Prior	74	630
Revolving	467	570
Revolving Converted to Term
Total	706	1,613
Commercial [Member] | Owner occupied RE [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	63,759	51,818
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	63,493	49,177
Loan balance classified by credit quality indicators, two years before latest fiscal year	45,922	190,161
Loan balance classified by credit quality indicators, three years before latest fiscal year	196,231	124,268
Loan balance classified by credit quality indicators, four years before latest fiscal year	124,560	75,389
Prior	211,333	160,386
Revolving	85	160
Revolving Converted to Term		238
Total	705,383	651,597
Commercial [Member] | Owner occupied RE [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	59,743	51,338
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	63,053	47,997
Loan balance classified by credit quality indicators, two years before latest fiscal year	40,074	186,361
Loan balance classified by credit quality indicators, three years before latest fiscal year	190,168	122,306
Loan balance classified by credit quality indicators, four years before latest fiscal year	122,283	66,561
Prior	197,552	145,743
Revolving	85	160
Revolving Converted to Term		238
Total	672,958	620,704
Commercial [Member] | Owner occupied RE [Member] | Watch [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	4,016	480
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	440	1,180
Loan balance classified by credit quality indicators, two years before latest fiscal year	5,848	3,638
Loan balance classified by credit quality indicators, three years before latest fiscal year	5,801	1,962
Loan balance classified by credit quality indicators, four years before latest fiscal year	2,277	8,828
Prior	10,325	11,012
Revolving
Revolving Converted to Term
Total	28,707	27,100
Commercial [Member] | Owner occupied RE [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year		162
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior	3,456	2,840
Revolving
Revolving Converted to Term
Total	3,456	3,002
Commercial [Member] | Owner occupied RE [Member] | Substandard [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year	262
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior		791
Revolving
Revolving Converted to Term
Total	262	791
Commercial [Member] | Non-owner occupied RE [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	60,224	50,685
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	62,417	71,471
Loan balance classified by credit quality indicators, two years before latest fiscal year	66,345	328,776
Loan balance classified by credit quality indicators, three years before latest fiscal year	311,023	163,475
Loan balance classified by credit quality indicators, four years before latest fiscal year	160,485	100,699
Prior	281,872	208,681
Revolving	471	360
Revolving Converted to Term	467	220
Total	943,304	924,367
Current period gross write-offs 2024
Current period gross write-offs 2023
Current period gross write-offs 2022
Current period gross write-offs 2021
Current period gross write-offs Prior		(1,029)
Current period gross write-offs Revolving
Current period gross write-offs Revolving Converted to Term
Current period gross write-offs Total		(1,029)
Current period gross write-offs 2020
Commercial [Member] | Non-owner occupied RE [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	60,224	50,685
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	61,653	70,517
Loan balance classified by credit quality indicators, two years before latest fiscal year	64,117	321,726
Loan balance classified by credit quality indicators, three years before latest fiscal year	302,806	145,658
Loan balance classified by credit quality indicators, four years before latest fiscal year	149,628	95,994
Prior	257,611	183,723
Revolving	471	360
Revolving Converted to Term	467	220
Total	896,977	868,883
Commercial [Member] | Non-owner occupied RE [Member] | Watch [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	618	954
Loan balance classified by credit quality indicators, two years before latest fiscal year	2,228	6,081
Loan balance classified by credit quality indicators, three years before latest fiscal year	5,970	10,238
Loan balance classified by credit quality indicators, four years before latest fiscal year	10,666	4,705
Prior	9,723	8,435
Revolving
Revolving Converted to Term
Total	29,205	30,413
Commercial [Member] | Non-owner occupied RE [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	146
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year		7,579
Loan balance classified by credit quality indicators, four years before latest fiscal year	191
Prior	7,627	8,882
Revolving
Revolving Converted to Term
Total	7,964	16,461
Commercial [Member] | Non-owner occupied RE [Member] | Substandard [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year		969
Loan balance classified by credit quality indicators, three years before latest fiscal year	2,247
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior	6,911	7,641
Revolving
Revolving Converted to Term
Total	9,158	8,610
Consumer [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	136,468	90,622
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	72,160	153,508
Loan balance classified by credit quality indicators, two years before latest fiscal year	140,246	302,849
Loan balance classified by credit quality indicators, three years before latest fiscal year	276,041	277,403
Loan balance classified by credit quality indicators, four years before latest fiscal year	263,270	169,008
Prior	303,998	167,895
Revolving	271,812	235,197
Revolving Converted to Term
Total	1,463,995	1,396,482
Consumer [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	15,623	7,700
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	4,507	3,636
Loan balance classified by credit quality indicators, two years before latest fiscal year	1,975	9,222
Loan balance classified by credit quality indicators, three years before latest fiscal year	3,089	316
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	648
Revolving Converted to Term
Total	25,842	20,874
Consumer [Member] | Real estate [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	119,220	79,987
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	66,810	148,940
Loan balance classified by credit quality indicators, two years before latest fiscal year	137,614	291,769
Loan balance classified by credit quality indicators, three years before latest fiscal year	271,484	275,062
Loan balance classified by credit quality indicators, four years before latest fiscal year	262,498	167,779
Prior	302,067	165,092
Revolving
Revolving Converted to Term
Total	1,159,693	1,128,629
Consumer [Member] | Home equity [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	239,996	204,897
Revolving Converted to Term
Total	239,996	204,897
Current period gross write-offs 2024
Current period gross write-offs 2023
Current period gross write-offs 2022
Current period gross write-offs 2021
Current period gross write-offs Prior
Current period gross write-offs Revolving		(45)
Current period gross write-offs Revolving Converted to Term
Current period gross write-offs Total		(45)
Current period gross write-offs 2020
Consumer [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	1,625	2,935
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	843	932
Loan balance classified by credit quality indicators, two years before latest fiscal year	657	1,858
Loan balance classified by credit quality indicators, three years before latest fiscal year	1,468	2,025
Loan balance classified by credit quality indicators, four years before latest fiscal year	772	1,229
Prior	1,931	2,803
Revolving	31,168	30,300
Revolving Converted to Term
Total	38,464	42,082
Current period gross write-offs 2025	(30)
Current period gross write-offs 2024
Current period gross write-offs 2023
Current period gross write-offs 2022
Current period gross write-offs 2021	(21)
Current period gross write-offs Prior		(38)
Current period gross write-offs Revolving	(9)	(42)
Current period gross write-offs Revolving Converted to Term
Current period gross write-offs Total	(60)	(80)
Current period gross write-offs 2020
Consumer [Member] | Pass [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	15,623	7,700
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	4,507	3,636
Loan balance classified by credit quality indicators, two years before latest fiscal year		9,222
Loan balance classified by credit quality indicators, three years before latest fiscal year	3,089	316
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	648
Revolving Converted to Term
Total	23,867	20,874
Consumer [Member] | Pass [Member] | Real estate [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	117,871	78,287
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	64,687	144,487
Loan balance classified by credit quality indicators, two years before latest fiscal year	130,511	277,854
Loan balance classified by credit quality indicators, three years before latest fiscal year	258,945	263,079
Loan balance classified by credit quality indicators, four years before latest fiscal year	250,683	160,007
Prior	283,170	153,584
Revolving
Revolving Converted to Term
Total	1,105,867	1,077,298
Consumer [Member] | Pass [Member] | Home equity [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	223,850	188,451
Revolving Converted to Term
Total	223,850	188,451
Consumer [Member] | Pass [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	1,586	2,732
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	658	836
Loan balance classified by credit quality indicators, two years before latest fiscal year	614	1,521
Loan balance classified by credit quality indicators, three years before latest fiscal year	1,121	1,593
Loan balance classified by credit quality indicators, four years before latest fiscal year	394	1,229
Prior	1,775	2,609
Revolving	31,018	29,660
Revolving Converted to Term
Total	37,166	40,180
Consumer [Member] | Watch [Member] | Construction [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year	1,975
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving
Revolving Converted to Term
Total	1,975
Consumer [Member] | Watch [Member] | Real estate [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	1,200	671
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	665	2,409
Loan balance classified by credit quality indicators, two years before latest fiscal year	4,539	6,961
Loan balance classified by credit quality indicators, three years before latest fiscal year	6,379	8,573
Loan balance classified by credit quality indicators, four years before latest fiscal year	8,474	4,147
Prior	9,577	4,632
Revolving
Revolving Converted to Term
Total	30,834	27,393
Consumer [Member] | Watch [Member] | Home equity [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	8,880	9,114
Revolving Converted to Term
Total	8,880	9,114
Consumer [Member] | Watch [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	25	167
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	156	61
Loan balance classified by credit quality indicators, two years before latest fiscal year	38	12
Loan balance classified by credit quality indicators, three years before latest fiscal year	29	366
Loan balance classified by credit quality indicators, four years before latest fiscal year	327
Prior	115	129
Revolving	131	595
Revolving Converted to Term
Total	821	1,330
Consumer [Member] | Special Mention [Member] | Real estate [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	149	817
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	817	1,536
Loan balance classified by credit quality indicators, two years before latest fiscal year	1,720	5,987
Loan balance classified by credit quality indicators, three years before latest fiscal year	5,174	2,664
Loan balance classified by credit quality indicators, four years before latest fiscal year	2,621	2,804
Prior	7,564	5,181
Revolving
Revolving Converted to Term
Total	18,045	18,989
Consumer [Member] | Special Mention [Member] | Home equity [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	5,757	6,173
Revolving Converted to Term
Total	5,757	6,173
Consumer [Member] | Special Mention [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year	14	36
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	29	35
Loan balance classified by credit quality indicators, two years before latest fiscal year	5	325
Loan balance classified by credit quality indicators, three years before latest fiscal year	318	66
Loan balance classified by credit quality indicators, four years before latest fiscal year	51
Prior	41	65
Revolving	19	45
Revolving Converted to Term
Total	477	572
Consumer [Member] | Substandard [Member] | Real estate [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year		212
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year	641	508
Loan balance classified by credit quality indicators, two years before latest fiscal year	844	967
Loan balance classified by credit quality indicators, three years before latest fiscal year	986	746
Loan balance classified by credit quality indicators, four years before latest fiscal year	720	821
Prior	1,756	1,695
Revolving
Revolving Converted to Term
Total	4,947	4,949
Consumer [Member] | Substandard [Member] | Home equity [Member]
Financing Receivable, Past Due [Line Items]
Loan balance classified by credit quality indicators, current fiscal year
Loan balance classified by credit quality indicators, fiscal year before latest fiscal year
Loan balance classified by credit quality indicators, two years before latest fiscal year
Loan balance classified by credit quality indicators, three years before latest fiscal year
Loan balance classified by credit quality indicators, four years before latest fiscal year
Prior
Revolving	1,509	1,159
Revolving Converted to Term
Total	$ 1,509	$ 1,159

X

- Definition

The gross amount of write-offs six years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2020
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs five years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2021
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs four years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2022
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs three years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2023
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs two years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2024
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs fiscal year prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffs2025
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs more than six years prior to current fiscal year.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffsPrior
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs revolving.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffsRevolving
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs revolving convert term.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffsRevolvingConvertTerm
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The gross amount of write-offs.

+ References

No definition available.

+ Details

Name:	SFST_CurrentPeriodGrossWriteoffsTotal
Namespace Prefix:	SFST_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amortized cost of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-14

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 80
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-80

+ Details

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

X

- Definition

Amortized cost of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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

X

- Definition

Amortized cost of revolving financing receivable converted to term loan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

+ Details

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

X

- Definition

Amortized cost, before allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477011/948-310-45-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 5: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-7A

Reference 6: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-29

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (1)
-Publisher SEC

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (2)
-Publisher SEC

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Regulation S-K (SK)
-Number 229
-Section 1404
-Paragraph a
-Publisher SEC

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 80
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-80

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-14

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=SFST_BusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=SFST_WatchMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=SFST_OtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: