Annual report pursuant to Section 13 and 15(d)

VARIABLE INTEREST ENTITIES (VIEs) (Additional Information) (Detail)

v2.4.1.9
VARIABLE INTEREST ENTITIES (VIEs) (Additional Information) (Detail) (USD $)
Dec. 31, 2014
Dec. 31, 2013
Variable Interest Entities [Line Items]    
Other Assets $ 11,543,000us-gaap_OtherAssets $ 12,213,000us-gaap_OtherAssets
Limited Partners' Capital Account 25,460,000us-gaap_LimitedPartnersCapitalAccount 26,005,000us-gaap_LimitedPartnersCapitalAccount
Partnership Investment [Member]    
Variable Interest Entities [Line Items]    
Other Assets 265,000us-gaap_OtherAssets
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= sfbs_PartnershipInvestmentMember 		313,000us-gaap_OtherAssets
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= sfbs_PartnershipInvestmentMember
Loan [Member]    
Variable Interest Entities [Line Items]    
Limited Partners' Capital Account $ 17,386,000us-gaap_LimitedPartnersCapitalAccount
/ us-gaap_ShortTermDebtTypeAxis
= sfbs_LoanMember 		$ 17,386,000us-gaap_LimitedPartnersCapitalAccount
/ us-gaap_ShortTermDebtTypeAxis
= sfbs_LoanMember