Quarterly report pursuant to Section 13 or 15(d)

LOANS (Loans By Performance Status) (Detail)

v2.4.1.9
LOANS (Loans By Performance Status) (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Financing Receivable Recorded Investment [Line Items]    
Loans $ 3,607,852us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome $ 3,359,858us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome [1]
Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,543,531us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember 		1,495,092us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 219,005us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember 		208,769us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 869,724us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember 		793,917us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 375,770us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember 		333,455us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 545,668us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember 		471,363us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,791,162us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember 		1,598,735us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 54,154us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember 		57,262us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Performing Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 3,598,938us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		3,349,808us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,542,818us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		1,493,995us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 213,732us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		203,720us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 869,000us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		793,234us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 374,804us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		331,859us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 545,094us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		470,404us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,788,898us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		1,595,497us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Performing Financing Receivable [Member] | Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 53,490us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember 		56,596us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
Nonperforming Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 8,914us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		10,050us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 713us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		1,097us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 5,273us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		5,049us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 724us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		683us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 966us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		1,596us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 574us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		959us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 2,264us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		3,238us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] | Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans $ 664us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember 		$ 666us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_NonperformingFinancingReceivableMember
[1] derived from audited financial statements