Quarterly report pursuant to Section 13 or 15(d)

LOANS (Loans By Credit Quality Indicator) (Detail)

v2.4.1.9
LOANS (Loans By Credit Quality Indicator) (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
Pass [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 3,513,847us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		3,282,232us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,494,527us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		1,459,356us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 207,722us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		197,727us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 856,894us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		784,492us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 368,705us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		326,316us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 532,569us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		457,782us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 1,758,168us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		1,568,590us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Pass [Member] | Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 53,430us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember 		56,559us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Special Mention [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 52,709us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		50,901us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 25,411us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		25,416us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 5,358us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		5,332us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 8,353us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		6,848us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 4,602us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		4,253us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 8,925us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		9,015us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 21,880us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		20,116us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Special Mention [Member] | Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 60us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember 		37us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SpecialMentionMember
Substandard [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 41,296us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		26,725us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 23,593us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		10,320us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 5,925us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		5,710us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 4,477us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		2,577us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 2,463us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		2,886us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 4,174us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		4,566us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 11,114us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember 		10,029us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Substandard [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_SubstandardMember 		666us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Doubtful [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Commercial Financial and Agricultural Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialFinancialAndAgriculturalFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Commercial Real Estate Construction Financing Receivable [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Commercial Mortgage Loans Owner Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_CommercialMortgageLoansOwnerOccupiedMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | One To Four Family Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OneToFourFamilyMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Other Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_OtherRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Residential Real Estate Mortgage Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= sfbs_ResidentialRealEstateMortgageLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
Doubtful [Member] | Consumer Portfolio Segment [Member]    
Financing Receivable Recorded Investment [Line Items]    
Loans $ 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember 		$ 0us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_DoubtfulMember
[1] derived from audited financial statements