Investment Securities (Details Narrative)	Jun. 30, 2024 Investments
Investments, Debt and Equity Securities [Abstract]
Number of investments	120

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

No definition available.

Name:	SFST_NumberOfInvestmentsInContinuousUnrealizedLossPositionLessThanTwelveMonth
Namespace Prefix:	SFST_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant