Annual report pursuant to Section 13 and 15(d)

DEPOSITS (Summary of Deposits) (Detail)

v2.4.1.9
DEPOSITS (Summary of Deposits) (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Summary of Deposits [Line Items]    
Deposits $ 3,398,160us-gaap_Deposits $ 3,019,642us-gaap_Deposits
Noninterest Bearing Demand [Member]    
Summary of Deposits [Line Items]    
Deposits 810,460us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_NoninterestBearingDemandMember 		650,456us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_NoninterestBearingDemandMember
Interest Bearing Checking [Member]    
Summary of Deposits [Line Items]    
Deposits 2,158,984us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_InterestBearingCheckingMember 		1,930,676us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_InterestBearingCheckingMember
Savings [Member]    
Summary of Deposits [Line Items]    
Deposits 29,125us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_SavingsMember 		23,890us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_SavingsMember
Time [Member]    
Summary of Deposits [Line Items]    
Deposits 205,414us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_TimeMember 		218,455us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_TimeMember
Time, over $250,000 [Member]    
Summary of Deposits [Line Items]    
Deposits $ 194,177us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_Time100000AndOverMember 		$ 196,165us-gaap_Deposits
/ sfbs_ClassOfDepositAxis
= sfbs_Time100000AndOverMember