Investment Securities (Details Textual)	Jun. 30, 2013 Investment	Dec. 31, 2012 Investment
Investment Securities (Textual)
Number of investments, Less than 12 months	41	20

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

No definition available.

Name:	sfst_NumberOfInvestmentsInContinuousUnrealizedLossPositionLessThanTwelveMonths
Namespace Prefix:	sfst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant