Annual report pursuant to Section 13 and 15(d)

PARENT COMPANY FINANCIAL INFORMATION (Condensed Statements of Income) (Detail)

v2.4.1.9
PARENT COMPANY FINANCIAL INFORMATION (Condensed Statements of Income) (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income:                      
Other income                 $ 1,006us-gaap_OtherIncome $ 878us-gaap_OtherIncome $ 744us-gaap_OtherIncome
Expense:                      
Net income                 52,377us-gaap_NetIncomeLoss 41,617us-gaap_NetIncomeLoss 34,445us-gaap_NetIncomeLoss
Dividends on preferred stock                 431us-gaap_PreferredStockDividendsIncomeStatementImpact 416us-gaap_PreferredStockDividendsIncomeStatementImpact 400us-gaap_PreferredStockDividendsIncomeStatementImpact
Net income available to common stockholders 14,917us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 13,902us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 11,469us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 11,658us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 11,752us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 10,712us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 9,586us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 9,151us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 51,946us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 41,201us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 34,045us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Parent Company [Member]                      
Income:                      
Dividends received from subsidiary                 12,000us-gaap_DividendIncomeOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
4,750us-gaap_DividendIncomeOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
0us-gaap_DividendIncomeOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Other income                 0us-gaap_OtherIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1us-gaap_OtherIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
41us-gaap_OtherIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Total income                 12,000us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
4,751us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
41us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Expense:                      
Other expenses                 1,183us-gaap_OtherCostAndExpenseOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1,147us-gaap_OtherCostAndExpenseOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1,594us-gaap_OtherCostAndExpenseOperating
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Total expenses                 1,183us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1,147us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1,594us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Equity in undistributed earnings of subsidiary                 41,529sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
37,997sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
35,998sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Net income                 52,346us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
41,601us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
34,445us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Dividends on preferred stock                 400us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
400us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
400us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Net income available to common stockholders                 $ 51,946us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
$ 41,201us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
$ 34,045us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember