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Aggregate value of restricted common stock, which are yet to be vested.

No definition available.

Name:	sfst_NonvestedRestrictedStockValue
Namespace Prefix:	sfst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.

Name:	us-gaap_AdditionalPaidInCapital
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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Name:	us-gaap_Assets
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

Name:	us-gaap_AvailableForSaleSecurities
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Period Type:	instant

The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.

Name:	us-gaap_BankOwnedLifeInsurance
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Period Type:	instant

For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

Name:	us-gaap_CashAndDueFromBanks
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Period Type:	instant

The sum of cash and cash equivalents plus Federal Funds Sold. Cash and cash equivalents consist of short term, highly liquid investments that are readily convertible to known amounts of cash and are so near their maturity that they present negligible risk of changes in value due to changes in interest rates -- usually with an original maturity less than 90 days.

Name:	us-gaap_CashCashEquivalentsAndFederalFundsSold
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Period Type:	instant

No definition available.

Name:	us-gaap_CashCashEquivalentsAndFederalFundsSoldAbstract
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Period Type:	duration

Value of all classes of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares exclude common shares repurchased by the entity and held as treasury shares.

Name:	us-gaap_CommonStockValueOutstanding
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Balance Type:	credit
Period Type:	instant

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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-Section 50
-Paragraph 2
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Name:	us-gaap_DeferredTaxAssetsLiabilitiesNet
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Balance Type:	debit
Period Type:	instant

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

Name:	us-gaap_Deposits
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Balance Type:	credit
Period Type:	instant

The amount outstanding of funds lent to other depository institutions, securities brokers, or securities dealers in the form of Federal Funds sold; for example, immediately available funds lent under agreements or contracts that mature in one business day or roll over under a continuing contract, regardless of the nature of the transaction or the collateral involved, excluding overnight lending for commercial and industrial purposes. Also include Federal Funds sold under agreements to resell on a gross basis, excluding (1) sales of term Federal Funds, (2) due bills representing purchases of securities or other assets by the reporting bank that have not yet been delivered and similar instruments, (3) resale agreements that mature in more than one business day involving assets other than securities, and (4) yield maintenance dollar repurchase agreements.

Name:	us-gaap_FederalFundsSold
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Balance Type:	debit
Period Type:	instant

For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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-Section 45
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-Subparagraph (SX 210.9-03.2)
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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

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-Subparagraph (SX 210.5-02(22))
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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

Name:	us-gaap_Liabilities
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Balance Type:	credit
Period Type:	instant

Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.

Name:	us-gaap_LiabilitiesAndStockholdersEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	us-gaap_LiabilitiesAndStockholdersEquityAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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-Subparagraph (b)(1)(ii)
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-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
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Balance Type:	credit
Period Type:	instant

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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-Subparagraph (SX 210.9-03.7)
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Name:	us-gaap_LoansAndLeasesReceivableNetReportedAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The face amount of loans that will be sold to other entities.

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

Amount of investment in marketable security.

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

No definition available.

Name:	us-gaap_MarketableSecuritiesAbstract
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Balance Type:	na
Period Type:	duration

Amount of assets classified as other.

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Name:	us-gaap_OtherAssets
Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

Amount of investments classified as other.

Name:	us-gaap_OtherInvestments
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of liabilities classified as other.

Name:	us-gaap_OtherLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Value of all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by shareholders, which is net of related treasury stock. May be all or a portion of the number of preferred shares authorized. These shares represent the ownership interest of the preferred shareholders.

Name:	us-gaap_PreferredStockValueOutstanding
Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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-Subparagraph (SX 210.5-02(14))
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-Name Accounting Standards Codification
-Topic 360
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-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

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

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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-Topic 505
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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Balance Type:	credit
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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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-Paragraph 2
-Subparagraph (SAB Topic 4.E)
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-Paragraph 1
-Subparagraph (SX 210.5-02(31))
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Namespace Prefix:	us-gaap_
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Period Type:	instant

No definition available.