Quarterly report pursuant to Section 13 or 15(d)

SECURITIES (Amortized Cost And Fair Value Of Contractual Securities) (Details 1)

v2.4.1.9
SECURITIES (Amortized Cost And Fair Value Of Contractual Securities) (Details 1) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Debt securities available for sale    
Amortized Cost $ 299,354us-gaap_AvailableForSaleSecuritiesAmortizedCost $ 291,403us-gaap_AvailableForSaleSecuritiesAmortizedCost
Fair Value 307,379us-gaap_AvailableForSaleSecurities 298,310us-gaap_AvailableForSaleSecurities
Debt securities held to maturity    
Amortized Cost 29,126us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment 29,355us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
Fair Value 29,886us-gaap_HeldToMaturitySecuritiesFairValue 29,974us-gaap_HeldToMaturitySecuritiesFairValue
Due within one year [Member]    
Debt securities available for sale    
Amortized Cost 17,111us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_DueWithinOneYearMember
16,944us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_DueWithinOneYearMember
Fair Value 17,232us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_DueWithinOneYearMember
17,246us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_DueWithinOneYearMember
Due from one to five years [Member]    
Debt securities available for sale    
Amortized Cost 126,487us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_DueFromOneToFiveYearsMember
121,591us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_DueFromOneToFiveYearsMember
Fair Value 129,405us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_DueFromOneToFiveYearsMember
123,962us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_DueFromOneToFiveYearsMember
Due from five to ten years [Member]    
Debt securities available for sale    
Amortized Cost 62,526us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
60,079us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
Fair Value 64,095us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
61,221us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
Debt securities held to maturity    
Amortized Cost 298us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
298us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
Fair Value 322us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
325us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= sfbs_FiveYearsToTenYearsMember
Due after ten years [Member]    
Debt securities available for sale    
Amortized Cost 350us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
350us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
Fair Value 383us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
358us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
Debt securities held to maturity    
Amortized Cost 5,254us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
5,253us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
Fair Value 5,720us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
5,716us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= sfbs_MoreThanTenYearsMember
Mortgage-backed securities [Member]    
Debt securities available for sale    
Amortized Cost 92,880us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
92,439us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
Fair Value 96,264us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
95,523us-gaap_AvailableForSaleSecurities
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
Debt securities held to maturity    
Amortized Cost 23,574us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
23,804us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
Fair Value $ 23,844us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember
$ 23,933us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_StatementScenarioAxis
= us-gaap_MortgageBackedSecuritiesMember