Quarterly report pursuant to Section 13 or 15(d)

SECURITIES (Investment Securities Continuous Unrealized Loss Position) (Details 2)

v2.4.1.9
SECURITIES (Investment Securities Continuous Unrealized Loss Position) (Details 2) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Gross Unrealized Losses $ (500)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses $ (659)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
Fair Value 45,661us-gaap_InvestmentsFairValueDisclosure 48,516us-gaap_InvestmentsFairValueDisclosure
U.S. Treasury and Government Sponsored Agencies [Member]    
Gross Unrealized Losses (67)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
Fair Value 4,964us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
Mortgage-Backed Securities [Member]    
Gross Unrealized Losses (268)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember 		(331)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
Fair Value 21,008us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember 		17,751us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
State and Municipal Securities [Member]    
Gross Unrealized Losses (165)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember 		(328)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Fair Value 19,689us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember 		30,765us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Corporate Debt [Member]    
Gross Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
Fair Value 0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
Less Than Twelve Months [Member]    
Gross Unrealized Losses (211)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		(162)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Fair Value 24,985us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		19,945us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Less Than Twelve Months [Member] | U.S. Treasury and Government Sponsored Agencies [Member]    
Gross Unrealized Losses (67)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Fair Value 4,964us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Less Than Twelve Months [Member] | Mortgage-Backed Securities [Member]    
Gross Unrealized Losses (62)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Fair Value 6,914us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Less Than Twelve Months [Member] | State and Municipal Securities [Member]    
Gross Unrealized Losses (82)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		(162)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Fair Value 13,107us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		19,945us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Less Than Twelve Months [Member] | Corporate Debt [Member]    
Gross Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Fair Value 0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_LessThanTwelveMonthsMember
Twelve Months Or More [Member]    
Gross Unrealized Losses (289)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		(497)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Fair Value 20,676us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		28,571us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Twelve Months Or More [Member] | U.S. Treasury and Government Sponsored Agencies [Member]    
Gross Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Fair Value 0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Twelve Months Or More [Member] | Mortgage-Backed Securities [Member]    
Gross Unrealized Losses (206)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		(331)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Fair Value 14,094us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		17,751us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_MortgageBackedSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Twelve Months Or More [Member] | State and Municipal Securities [Member]    
Gross Unrealized Losses (83)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		(166)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Fair Value 6,582us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		10,820us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Twelve Months Or More [Member] | Corporate Debt [Member]    
Gross Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember
Fair Value $ 0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember 		$ 0us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_GainLossOnInvestmentsByCategoryAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_StatementScenarioAxis
= sfbs_TwelveMonthsOrMoreMember