Loans Receivable, Net (Summary of loans restructured as Troubled Debt Restructurings) (Details) (USD $)	9 Months Ended	12 Months Ended
Dec. 31, 2012 loan	Dec. 31, 2014 loan	Dec. 31, 2013 loan
Financing Receivable, Modifications [Line Items]
Number of Contracts - Troubled Debt Restructurings	1	2	5
Pre- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	$ 257,452	$ 186,188	$ 1,442,543
Post- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	257,452	186,188	1,442,543
Number of Contracts - Troubled Debt Restructurings That Subsequently Defaulted During the Period	4	1	1
Recorded Investment - Troubled Debt Restructurings That Subsequently Defaulted During the Period	880,745	66,138	146,267
Residential Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts - Troubled Debt Restructurings	0	0	0
Pre- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	0
Post- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	0
Number of Contracts - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Recorded Investment - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Consumer Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts - Troubled Debt Restructurings	0	0	0
Pre- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	0
Post- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	0
Number of Contracts - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Recorded Investment - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Commercial Business
Financing Receivable, Modifications [Line Items]
Number of Contracts - Troubled Debt Restructurings	0	0	1
Pre- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	32,850
Post- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	0	0	32,850
Number of Contracts - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Recorded Investment - Troubled Debt Restructurings That Subsequently Defaulted During the Period	0	0	0
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts - Troubled Debt Restructurings	1	2	4
Pre- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	257,452	186,188	1,409,693
Post- Modification Outstanding Recorded Investment - Troubled Debt Restructurings	257,452	186,188	1,409,693
Number of Contracts - Troubled Debt Restructurings That Subsequently Defaulted During the Period	4	1	1
Recorded Investment - Troubled Debt Restructurings That Subsequently Defaulted During the Period	$ 880,745	$ 66,138	$ 146,267

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

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953682-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=sfdl_CommercialBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=sfdl_CommercialRealEstate1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=sfdl_ConsumerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=sfdl_ResidentialRealEstate1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: