Annual report pursuant to Section 13 and 15(d)

PARENT COMPANY FINANCIAL INFORMATION (Statements of Cash Flow) (Detail)

v2.4.1.9
PARENT COMPANY FINANCIAL INFORMATION (Statements of Cash Flow) (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Operating activities      
Net income $ 52,377us-gaap_NetIncomeLoss $ 41,617us-gaap_NetIncomeLoss $ 34,445us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash used in operating activities:      
Net cash (used in) provided by operating activities 64,115us-gaap_NetCashProvidedByUsedInOperatingActivities 74,198us-gaap_NetCashProvidedByUsedInOperatingActivities 41,184us-gaap_NetCashProvidedByUsedInOperatingActivities
Investing activities      
Net cash used in investing activities (549,092)us-gaap_NetCashProvidedByUsedInInvestingActivities (571,693)us-gaap_NetCashProvidedByUsedInInvestingActivities (509,808)us-gaap_NetCashProvidedByUsedInInvestingActivities
Financing activities      
Proceeds from other borrowings 0us-gaap_ProceedsFromOtherDebt 0us-gaap_ProceedsFromOtherDebt 19,917us-gaap_ProceedsFromOtherDebt
Repayment of subordinated debentures 0sfbs_Redemptionofsubordinateddebentures 0sfbs_Redemptionofsubordinateddebentures (15,464)sfbs_Redemptionofsubordinateddebentures
Proceeds from issuance of common stock, net 250us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock 0us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock 0us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock
Dividends paid on common stock (3,609)us-gaap_PaymentsOfDividendsCommonStock (3,682)us-gaap_PaymentsOfDividendsCommonStock (3,134)us-gaap_PaymentsOfDividendsCommonStock
Dividends paid on preferred stock (431)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock (416)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock (400)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock
Net cash provided by financing activities 524,026us-gaap_NetCashProvidedByUsedInFinancingActivities 575,165us-gaap_NetCashProvidedByUsedInFinancingActivities 406,436us-gaap_NetCashProvidedByUsedInFinancingActivities
Increase (decrease) in cash and cash equivalents 39,049us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease 77,670us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease (62,188)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Cash and cash equivalents at beginning of year 258,415us-gaap_CashAndCashEquivalentsAtCarryingValue 180,745us-gaap_CashAndCashEquivalentsAtCarryingValue 242,933us-gaap_CashAndCashEquivalentsAtCarryingValue
Cash and cash equivalents at end of year 297,464us-gaap_CashAndCashEquivalentsAtCarryingValue 258,415us-gaap_CashAndCashEquivalentsAtCarryingValue 180,745us-gaap_CashAndCashEquivalentsAtCarryingValue
Parent Company [Member]      
Operating activities      
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
Adjustments to reconcile net income to net cash used in operating activities:      
Other 165us-gaap_PaymentsForOtherOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(224)us-gaap_PaymentsForOtherOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
878us-gaap_PaymentsForOtherOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Equity in undistributed earnings of subsidiary (41,529)sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(37,997)sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(35,998)sfbs_EquityInUndistributedEarningsOfSubsidiary
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Net cash (used in) provided by operating activities 10,982us-gaap_NetCashProvidedByUsedInOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
3,380us-gaap_NetCashProvidedByUsedInOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(675)us-gaap_NetCashProvidedByUsedInOperatingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Investing activities      
Investment in subsidiary 0us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(10,499)us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
0us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Net cash used in investing activities 0us-gaap_NetCashProvidedByUsedInInvestingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(10,499)us-gaap_NetCashProvidedByUsedInInvestingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
0us-gaap_NetCashProvidedByUsedInInvestingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Financing activities      
Proceeds from other borrowings 0us-gaap_ProceedsFromOtherDebt
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
0us-gaap_ProceedsFromOtherDebt
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
19,917us-gaap_ProceedsFromOtherDebt
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Repayment of subordinated debentures 0sfbs_Redemptionofsubordinateddebentures
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
0sfbs_Redemptionofsubordinateddebentures
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(15,464)sfbs_Redemptionofsubordinateddebentures
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Proceeds from issuance of common stock, net 52,076us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
10,499us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
112us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Dividends paid on common stock (3,609)us-gaap_PaymentsOfDividendsCommonStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(3,682)us-gaap_PaymentsOfDividendsCommonStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(3,134)us-gaap_PaymentsOfDividendsCommonStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Dividends paid on preferred stock (400)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(400)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(400)us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Net cash provided by financing activities 48,067us-gaap_NetCashProvidedByUsedInFinancingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
6,417us-gaap_NetCashProvidedByUsedInFinancingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
1,031us-gaap_NetCashProvidedByUsedInFinancingActivities
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Increase (decrease) in cash and cash equivalents 59,049us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(702)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
356us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Cash and cash equivalents at beginning of year 2,562us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
3,264us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
2,908us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Cash and cash equivalents at end of year $ 61,611us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
$ 2,562us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
$ 3,264us-gaap_CashAndCashEquivalentsAtCarryingValue
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember