Advances From Federal Home Loan Bank (FHLB) And Other Borrowings (Callable FHLB advances) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Schedule of Federal Home Loan Bank Advances [Line Items]
Advances From FHLB	$ 34,640,000	$ 52,900,000
Amount of Additional Borrowing Capacity	240,200,000	$ 195,700,000
Federal Home Loan Bank Advances November 29, 2006 [Member]
Schedule of Federal Home Loan Bank Advances [Line Items]
Advances From FHLB	$ 5,000,000
Advances from FHLB, Interest Rate at Period End	4.025%
Federal Home Loan Bank Advances May 24, 2007 [Member]
Schedule of Federal Home Loan Bank Advances [Line Items]
Advances From FHLB	$ 7,900,000
Advances from FHLB, Interest Rate at Period End	4.375%
Federal Home Loan Bank Advances July 25, 2007 [Member]
Schedule of Federal Home Loan Bank Advances [Line Items]
Advances From FHLB	$ 5,000,000
Advances from FHLB, Interest Rate at Period End	4.396%

[Line Items] for Schedule of Federal Home Loan Bank Advances [Table]

No definition available.

Name:	sfdl_ScheduleOfFederalHomeLoanBankAdvancesLineItems
Namespace Prefix:	sfdl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

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

- Definition

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22 (b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

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

- Definition

States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	sfdl_FederalHomeLoanBankAdvancesBorrowDateAxis=sfdl_FederalHomeLoanBankAdvancesNovember292006Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	sfdl_FederalHomeLoanBankAdvancesBorrowDateAxis=sfdl_FederalHomeLoanBankAdvancesMay242007Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	sfdl_FederalHomeLoanBankAdvancesBorrowDateAxis=sfdl_FederalHomeLoanBankAdvancesJuly252007Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: