$SBSI
SOUTHSIDE BANCSHARES INC Stock $sbsi

$sbsi Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-Q Financial Statement

#000070543221000177 Filed on October 29, 2021

Income Statement

Concept	2021 Q4	2021 Q3	2020 Q3
Revenue		$55.08M	$55.68M
YoY Change		-1.08%	-8.06%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$2.800M	$2.800M	$3.000M
YoY Change	-6.67%	-6.67%	0.0%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense		$6.870M	$9.091M
YoY Change		-24.43%	-50.0%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$33.50M	$34.28M	$30.86M
YoY Change	-1.0%	11.1%	31.57%
Income Tax	$4.810M	$5.000M	$3.800M
% Of Pretax Income	14.36%	14.58%	12.31%
Net Earnings	$28.69M	$29.31M	$27.07M
YoY Change	-2.98%	8.24%	36.79%
Net Earnings / Revenue		53.21%	48.63%
Basic Earnings Per Share		$0.90	$0.82
Diluted Earnings Per Share	$883.0K	$0.90	$0.82
COMMON SHARES
Basic Shares Outstanding	32.28M shares	32.47M shares	33.05M shares
Diluted Shares Outstanding		32.56M shares	33.10M shares

Balance Sheet

Concept	2021 Q4	2021 Q3	2020 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$201.8M	$87.13M	$96.20M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$142.5M	$142.7M	$147.2M
YoY Change	-1.43%	-3.01%	3.87%
Goodwill	$201.1M	$201.1M	$201.1M
YoY Change	0.0%	0.0%	0.01%
Intangibles	$6.895M	$7.553M	$10.57M
YoY Change	-29.24%	-28.54%	-26.56%
Long-Term Investments	$11.80M	$11.80M	$12.10M
YoY Change	-0.84%	-2.48%	-2.42%
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$7.260B	$7.136B	$7.191B
YoY Change	3.59%	-0.77%	9.92%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$16.70M	$17.00M	$17.90M
YoY Change	0.0%	-5.03%	70.48%
Deferred Revenue
YoY Change
Short-Term Debt	$23.20M	$20.70M	$41.60M
YoY Change	0.0%	-50.24%	333.33%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$16.70M	$17.00M	$17.90M
YoY Change	0.0%	-5.03%	70.48%
LONG-TERM LIABILITIES
Long-Term Debt	$158.8M	$158.8M	$159.0M
YoY Change	-38.33%	-0.13%	0.13%
Other Long-Term Liabilities	$64.60M	$58.00M	$67.80M
YoY Change	17.24%	-14.45%	-9.6%
Total Long-Term Liabilities	$223.4M	$216.8M	$226.8M
YoY Change	-28.53%	-4.41%	-2.99%
TOTAL LIABILITIES
Total Short-Term Liabilities	$16.70M	$17.00M	$17.90M
Total Long-Term Liabilities	$223.4M	$216.8M	$226.8M
Total Liabilities	$6.347B	$6.258B	$6.352B
YoY Change	3.5%	-1.48%	10.82%
SHAREHOLDERS EQUITY
Retained Earnings	$179.8M	$163.8M	$93.92M
YoY Change	61.69%	74.42%	26.1%
Common Stock	$828.0M	$826.1M	$818.0M
YoY Change	1.1%	0.98%	0.64%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$155.3M	$156.0M	$119.1M
YoY Change	25.33%	30.98%	27.26%
Treasury Stock Shares	5.617M shares	5.687M shares	4.850M shares
Shareholders Equity	$912.2M	$877.9M	$839.1M
YoY Change
Total Liabilities & Shareholders Equity	$7.260B	$7.136B	$7.191B
YoY Change	3.59%	-0.77%	9.92%

Cashflow Statement

Concept	2021 Q4	2021 Q3	2020 Q3
OPERATING ACTIVITIES
Net Income	$28.69M	$29.31M	$27.07M
YoY Change	-2.98%	8.24%	36.79%
Depreciation, Depletion And Amortization	$2.800M	$2.800M	$3.000M
YoY Change	-6.67%	-6.67%	0.0%
Cash From Operating Activities	$27.40M	$48.50M	$32.80M
YoY Change	-31.84%	47.87%	30.16%
INVESTING ACTIVITIES
Capital Expenditures	-$1.900M	-$2.000M	-$2.300M
YoY Change	58.33%	-13.04%	-34.29%
Acquisitions
YoY Change
Other Investing Activities	$22.00M	-$72.30M	$113.1M
YoY Change	-89.07%	-163.93%	-162.8%
Cash From Investing Activities	$20.10M	-$74.30M	$110.7M
YoY Change	-89.96%	-167.12%	-160.26%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	67.00M	-15.50M	-148.1M
YoY Change	-129.37%	-89.53%	-205.18%
NET CHANGE
Cash From Operating Activities	27.40M	48.50M	32.80M
Cash From Investing Activities	20.10M	-74.30M	110.7M
Cash From Financing Activities	67.00M	-15.50M	-148.1M
Net Change In Cash	114.5M	-41.30M	-4.600M
YoY Change	838.52%	797.83%	-74.01%
FREE CASH FLOW
Cash From Operating Activities	$27.40M	$48.50M	$32.80M
Capital Expenditures	-$1.900M	-$2.000M	-$2.300M
Free Cash Flow	$29.30M	$50.50M	$35.10M
YoY Change	-29.23%	43.87%	22.3%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0000705432
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2021-09-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	000-12247
	dei	Entity Registrant Name EntityRegistrantName	SOUTHSIDE BANCSHARES, INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	TX
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	75-1848732
	dei	Entity Address Address Line1 EntityAddressAddressLine1	1201 S. Beckham Avenue,
	dei	Entity Address City Or Town EntityAddressCityOrTown	Tyler,
	dei	Entity Address State Or Province EntityAddressStateOrProvince	TX
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	75701
	dei	City Area Code CityAreaCode	903
	dei	Local Phone Number LocalPhoneNumber	531-7111
	dei	Security12b Title Security12bTitle	Common Stock, $1.25 par value
	dei	Trading Symbol TradingSymbol	SBSI
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
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CY2021Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	53277000	USD
CY2020Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	51332000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	153699000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	112812000	USD
CY2021Q3	sbsi	Fee And Commissions Depositor Account FeeAndCommissionsDepositorAccount	6779000	USD
CY2020Q3	sbsi	Fee And Commissions Depositor Account FeeAndCommissionsDepositorAccount	6129000	USD
	sbsi	Fee And Commissions Depositor Account FeeAndCommissionsDepositorAccount	19513000	USD
	sbsi	Fee And Commissions Depositor Account FeeAndCommissionsDepositorAccount	17940000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	1381000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	78000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	3399000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	8281000	USD
CY2021Q3	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	299000	USD
CY2020Q3	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1071000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1285000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1924000	USD
CY2021Q3	sbsi	Fees And Commissions Fiduciary And Trust Activity FeesAndCommissionsFiduciaryAndTrustActivity	1494000	USD
CY2020Q3	sbsi	Fees And Commissions Fiduciary And Trust Activity FeesAndCommissionsFiduciaryAndTrustActivity	1253000	USD
	sbsi	Fees And Commissions Fiduciary And Trust Activity FeesAndCommissionsFiduciaryAndTrustActivity	4373000	USD
	sbsi	Fees And Commissions Fiduciary And Trust Activity FeesAndCommissionsFiduciaryAndTrustActivity	3779000	USD
CY2021Q3	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	637000	USD
CY2020Q3	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	680000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1908000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1899000	USD
CY2021Q3	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	846000	USD
CY2020Q3	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	564000	USD
	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	2476000	USD
	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	1643000	USD
CY2021Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	1333000	USD
CY2020Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	1366000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	4371000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	3366000	USD
CY2021Q3	us-gaap	Noninterest Income NoninterestIncome	12769000	USD
CY2020Q3	us-gaap	Noninterest Income NoninterestIncome	11141000	USD
	us-gaap	Noninterest Income NoninterestIncome	37325000	USD
	us-gaap	Noninterest Income NoninterestIncome	38832000	USD
CY2021Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	19777000	USD
CY2020Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	19344000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	59825000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	57616000	USD
CY2021Q3	us-gaap	Occupancy Net OccupancyNet	3532000	USD
CY2020Q3	us-gaap	Occupancy Net OccupancyNet	3595000	USD
	us-gaap	Occupancy Net OccupancyNet	10698000	USD
	us-gaap	Occupancy Net OccupancyNet	10574000	USD
CY2021Q3	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	579000	USD
CY2020Q3	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	519000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1491000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1643000	USD
CY2021Q3	sbsi	Atm Expense ATMExpense	311000	USD
CY2020Q3	sbsi	Atm Expense ATMExpense	271000	USD
	sbsi	Atm Expense ATMExpense	821000	USD
	sbsi	Atm Expense ATMExpense	728000	USD
CY2021Q3	us-gaap	Professional Fees ProfessionalFees	1135000	USD
CY2020Q3	us-gaap	Professional Fees ProfessionalFees	961000	USD
	us-gaap	Professional Fees ProfessionalFees	3166000	USD
	us-gaap	Professional Fees ProfessionalFees	3238000	USD
CY2021Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1503000	USD
CY2020Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1215000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	4221000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	3737000	USD
CY2021Q3	us-gaap	Communication Communication	552000	USD
CY2020Q3	us-gaap	Communication Communication	495000	USD
	us-gaap	Communication Communication	1689000	USD
	us-gaap	Communication Communication	1494000	USD
CY2021Q3	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	454000	USD
CY2020Q3	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	469000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1343000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	668000	USD
CY2021Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	695000	USD
CY2020Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	881000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2191000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2792000	USD
CY2021Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1118000	USD
CY2020Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1118000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2021Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	2107000	USD
CY2020Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	3866000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	7133000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	9502000	USD
CY2021Q3	us-gaap	Noninterest Expense NoninterestExpense	31763000	USD
CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	31616000	USD
	us-gaap	Noninterest Expense NoninterestExpense	93696000	USD
	us-gaap	Noninterest Expense NoninterestExpense	91992000	USD
CY2021Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	34283000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	30857000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	97328000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	59652000	USD
CY2021Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	4977000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3783000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12614000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7071000	USD
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	29306000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	27074000	USD
	us-gaap	Net Income Loss NetIncomeLoss	84714000	USD
	us-gaap	Net Income Loss NetIncomeLoss	52581000	USD
CY2021Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.90
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.60
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.58
CY2021Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.90
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.82
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.59
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.58
CY2021Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.33
CY2020Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.31
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.98
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.93
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	29306000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	27074000	USD
	us-gaap	Net Income Loss NetIncomeLoss	84714000	USD
	us-gaap	Net Income Loss NetIncomeLoss	52581000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Reclassification Adjustments And Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeReclassificationAdjustmentsAndTax	-27714000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Reclassification Adjustments And Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeReclassificationAdjustmentsAndTax	1601000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Reclassification Adjustments And Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeReclassificationAdjustmentsAndTax	-43527000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Reclassification Adjustments And Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeReclassificationAdjustmentsAndTax	88900000	USD
CY2021Q3	sbsi	Amortizationof Unrealized Gains Losseson Securities Transferred Between Availablefor Sale And Heldto Maturity Debt Securities Before Tax AmortizationofUnrealizedGainsLossesonSecuritiesTransferredBetweenAvailableforSaleAndHeldtoMaturityDebtSecuritiesBeforeTax	-312000	USD
CY2020Q3	sbsi	Amortizationof Unrealized Gains Losseson Securities Transferred Between Availablefor Sale And Heldto Maturity Debt Securities Before Tax AmortizationofUnrealizedGainsLossesonSecuritiesTransferredBetweenAvailableforSaleAndHeldtoMaturityDebtSecuritiesBeforeTax	-394000	USD
	sbsi	Amortizationof Unrealized Gains Losseson Securities Transferred Between Availablefor Sale And Heldto Maturity Debt Securities Before Tax AmortizationofUnrealizedGainsLossesonSecuritiesTransferredBetweenAvailableforSaleAndHeldtoMaturityDebtSecuritiesBeforeTax	-1118000	USD
	sbsi	Amortizationof Unrealized Gains Losseson Securities Transferred Between Availablefor Sale And Heldto Maturity Debt Securities Before Tax AmortizationofUnrealizedGainsLossesonSecuritiesTransferredBetweenAvailableforSaleAndHeldtoMaturityDebtSecuritiesBeforeTax	-730000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	1381000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	78000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	3399000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	8281000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	377000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-197000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	8296000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-25236000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-1617000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-1587000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-4784000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-2283000	USD
CY2021Q3	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Gain Lossand Prior Service Cost Credit Reclassification Adjustmentfrom Aoc Ibefore Tax OtherComprehensiveIncomeLossDefinedBenefitPlanGainLossandPriorServiceCostCreditReclassificationAdjustmentfromAOCIbeforeTax	316000	USD
CY2020Q3	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Gain Lossand Prior Service Cost Credit Reclassification Adjustmentfrom Aoc Ibefore Tax OtherComprehensiveIncomeLossDefinedBenefitPlanGainLossandPriorServiceCostCreditReclassificationAdjustmentfromAOCIbeforeTax	819000	USD
	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Gain Lossand Prior Service Cost Credit Reclassification Adjustmentfrom Aoc Ibefore Tax OtherComprehensiveIncomeLossDefinedBenefitPlanGainLossandPriorServiceCostCreditReclassificationAdjustmentfromAOCIbeforeTax	948000	USD
	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Gain Lossand Prior Service Cost Credit Reclassification Adjustmentfrom Aoc Ibefore Tax OtherComprehensiveIncomeLossDefinedBenefitPlanGainLossandPriorServiceCostCreditReclassificationAdjustmentfromAOCIbeforeTax	2207000	USD
CY2021Q3	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Prior Service Cost Credit Plan Amendment Before Tax OtherComprehensiveIncomeLossDefinedBenefitPlanPriorServiceCostCreditPlanAmendmentBeforeTax	0	USD
CY2020Q3	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Prior Service Cost Credit Plan Amendment Before Tax OtherComprehensiveIncomeLossDefinedBenefitPlanPriorServiceCostCreditPlanAmendmentBeforeTax	0	USD
	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Prior Service Cost Credit Plan Amendment Before Tax OtherComprehensiveIncomeLossDefinedBenefitPlanPriorServiceCostCreditPlanAmendmentBeforeTax	0	USD
	sbsi	Other Comprehensive Income Loss Defined Benefit Plan Prior Service Cost Credit Plan Amendment Before Tax OtherComprehensiveIncomeLossDefinedBenefitPlanPriorServiceCostCreditPlanAmendmentBeforeTax	163000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	0	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	0	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	0	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-7558000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-26473000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	4126000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-31780000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	53208000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-5560000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	866000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-6674000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	11173000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-20913000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	3260000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-25106000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	42035000	USD
CY2021Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	8393000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	30334000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	59608000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	94616000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	875297000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	34091000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-29494000	USD
CY2021Q1	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	8918	shares
CY2021Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	332000	USD
CY2021Q1	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	427396	shares
CY2021Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	15213000	USD
CY2021Q1	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	674000	USD
CY2021Q1	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	126260	shares
CY2021Q1	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	3386000	USD
CY2021Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.32
CY2021Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10476000	USD
CY2021Q1	us-gaap	Stockholders Equity StockholdersEquity	858597000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	21317000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	25301000	USD
CY2021Q2	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	7780	shares
CY2021Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	330000	USD
CY2021Q2	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	90884	shares
CY2021Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	3497000	USD
CY2021Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	686000	USD
CY2021Q2	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	99217	shares
CY2021Q2	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	2441000	USD
CY2021Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.33
CY2021Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10775000	USD
CY2021Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	829000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	894400000	USD
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	29306000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-20913000	USD
CY2021Q3	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	8631	shares
CY2021Q3	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	324000	USD
CY2021Q3	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	420204	shares
CY2021Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	15438000	USD
CY2021Q3	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	9426	shares
CY2021Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	64000	USD
CY2021Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.33
CY2021Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10706000	USD
CY2021Q3	us-gaap	Stockholders Equity StockholdersEquity	877866000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	804580000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	3953000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	29303000	USD
CY2020Q1	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	10607	shares
CY2020Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	347000	USD
CY2020Q1	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	869723	shares
CY2020Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	25842000	USD
CY2020Q1	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	695000	USD
CY2020Q1	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	47428	shares
CY2020Q1	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	1088000	USD
CY2020Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.31
CY2020Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10494000	USD
CY2020Q1	us-gaap	Stockholders Equity StockholdersEquity	795800000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	21554000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	9472000	USD
CY2020Q2	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	11532	shares
CY2020Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	336000	USD
CY2020Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	772000	USD
CY2020Q2	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	9342	shares
CY2020Q2	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-96000	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.31
CY2020Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10233000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	817605000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	27074000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	3260000	USD
CY2020Q3	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	12201	shares
CY2020Q3	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	337000	USD
CY2020Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	786000	USD
CY2020Q3	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	27477	shares
CY2020Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	331000	USD
CY2020Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.31
CY2020Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10245000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	839148000	USD
	us-gaap	Profit Loss ProfitLoss	84714000	USD
	us-gaap	Profit Loss ProfitLoss	52581000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	8634000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	9128000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-17709000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-17954000	USD
	us-gaap	Investment Income Net Amortization Of Discount And Premium InvestmentIncomeNetAmortizationOfDiscountAndPremium	649000	USD
	us-gaap	Investment Income Net Amortization Of Discount And Premium InvestmentIncomeNetAmortizationOfDiscountAndPremium	847000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-13543000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	25746000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	2189000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	2253000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3612000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-4305000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	3399000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	8281000	USD
	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	-315000	USD
	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	-821000	USD
	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	36961000	USD
	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	48343000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	34397000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	56646000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	180000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-129000	USD
	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Curtailments DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments	0	USD
	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Curtailments DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments	-163000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1118000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-9611000	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	1987000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	2803000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	35530000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-1223000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-3673000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	19981000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	4402000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	128650000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	50251000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	569807000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	821232000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	104728000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	291581000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	243507000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	316072000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	16602000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	19820000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	19240000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	20000000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	21113000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	5483000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-9314000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	222342000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	6491000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	797000	USD
	us-gaap	Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans	277000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	247000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	10216000	USD
	us-gaap	Payments For Proceeds From Life Insurance Policies PaymentsForProceedsFromLifeInsurancePolicies	13000000	USD
	us-gaap	Payments For Proceeds From Life Insurance Policies PaymentsForProceedsFromLifeInsurancePolicies	12500000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	1853000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	114000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	158000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-214123000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-423751000	USD
	us-gaap	Net Change Interest And Noninterest Bearing Deposits Domestic NetChangeInterestAndNoninterestBearingDepositsDomestic	399303000	USD
	us-gaap	Net Change Interest And Noninterest Bearing Deposits Domestic NetChangeInterestAndNoninterestBearingDepositsDomestic	420068000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-2448000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	13210000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	11648180000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	10135401000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	11821503000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	10155201000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	-95000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	0	USD
	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	100011000	USD
	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	6108000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1502000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	217000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	179000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	34148000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	25842000	USD
	us-gaap	Proceeds From Issuance Of Common Stock Dividend Reinvestment Plan ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	986000	USD
	us-gaap	Proceeds From Issuance Of Common Stock Dividend Reinvestment Plan ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	1020000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	31957000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	30972000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	64198000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	359007000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-21275000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-14493000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	108408000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	110697000	USD
CY2021Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	87133000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	96204000	USD
	us-gaap	Interest Paid Net InterestPaidNet	22295000	USD
	us-gaap	Interest Paid Net InterestPaidNet	40039000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	8750000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	9000000	USD
	sbsi	Loans Transferred To Other Repossessed Assets And Real Estate Through Foreclosure LoansTransferredToOtherRepossessedAssetsAndRealEstateThroughForeclosure	740000	USD
	sbsi	Loans Transferred To Other Repossessed Assets And Real Estate Through Foreclosure LoansTransferredToOtherRepossessedAssetsAndRealEstateThroughForeclosure	627000	USD
CY2021Q3	sbsi	Unsettled Trades To Purchase Securities Liability UnsettledTradesToPurchaseSecuritiesLiability	4433000	USD
CY2020Q3	sbsi	Unsettled Trades To Purchase Securities Liability UnsettledTradesToPurchaseSecuritiesLiability	7294000	USD
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	29306000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	27074000	USD
	us-gaap	Net Income Loss NetIncomeLoss	84714000	USD
	us-gaap	Net Income Loss NetIncomeLoss	52581000	USD
CY2021Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	32465000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	33047000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	32641000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	33250000	shares
CY2021Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	91000	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	51000	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	118000	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	81000	shares
CY2021Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	32556000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	33098000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	32759000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	33331000	shares
CY2021Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.90
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.60
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.58
CY2021Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.90
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.82
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.59
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.58
CY2021Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	462000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	288000	shares
CY2020Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	835000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	811000	shares
CY2021Q3	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-681000	USD
CY2020Q3	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-2150000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-2726000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	2418000	USD
CY2021Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2650237000	USD
CY2021Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	110187000	USD
CY2021Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	7320000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2753104000	USD
CY2021Q3	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	92479000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	5556000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2021Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	98035000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2437513000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	150074000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	282000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2587305000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	108998000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	9200000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	118198000	USD
CY2021Q3	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	1480000000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	1560000000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	433487000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	7043000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	4602000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	277000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	438089000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	7320000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	39898000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	282000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	39898000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	282000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Period Increase Decrease DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease	0	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	0	USD
	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	0	USD
CY2021Q3	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	0	USD
CY2020Q3	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	0	USD
CY2021Q3	sbsi	Transferred Securities Unrealized Loss Before Tax TransferredSecuritiesUnrealizedLossBeforeTax	1700000	USD
CY2021Q3	sbsi	Securities Transferred Unrealized Loss Net Of Tax SecuritiesTransferredUnrealizedLossNetOfTax	1400000	USD
CY2020Q4	sbsi	Transferred Securities Unrealized Loss Before Tax TransferredSecuritiesUnrealizedLossBeforeTax	2900000	USD
CY2020Q4	sbsi	Securities Transferred Unrealized Loss Net Of Tax SecuritiesTransferredUnrealizedLossNetOfTax	2300000	USD
	sbsi	Securities Transferred From Available For Sale To Held To Maturity SecuritiesTransferredFromAvailableForSaleToHeldToMaturity	0	USD
CY2020	sbsi	Securities Transferred From Available For Sale To Held To Maturity SecuritiesTransferredFromAvailableForSaleToHeldToMaturity	0	USD
CY2021Q3	us-gaap	Debt Securities Held To Maturity Nonaccrual DebtSecuritiesHeldToMaturityNonaccrual	0	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Nonaccrual DebtSecuritiesHeldToMaturityNonaccrual	0	USD
CY2021Q3	us-gaap	Interest Income Securities Us Treasury And Other Us Government InterestIncomeSecuritiesUSTreasuryAndOtherUSGovernment	182000	USD
CY2020Q3	us-gaap	Interest Income Securities Us Treasury And Other Us Government InterestIncomeSecuritiesUSTreasuryAndOtherUSGovernment	0	USD
CY2021Q3	us-gaap	Interest Income Securities State And Municipal InterestIncomeSecuritiesStateAndMunicipal	12223000	USD
CY2020Q3	us-gaap	Interest Income Securities State And Municipal InterestIncomeSecuritiesStateAndMunicipal	9787000	USD
CY2021Q3	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	1097000	USD
CY2020Q3	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	391000	USD
CY2021Q3	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	4405000	USD
CY2020Q3	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	7048000	USD
CY2021Q3	us-gaap	Interest And Other Income InterestAndOtherIncome	17907000	USD
CY2020Q3	us-gaap	Interest And Other Income InterestAndOtherIncome	17226000	USD
	us-gaap	Interest Income Securities Us Treasury And Other Us Government InterestIncomeSecuritiesUSTreasuryAndOtherUSGovernment	388000	USD
	us-gaap	Interest Income Securities Us Treasury And Other Us Government InterestIncomeSecuritiesUSTreasuryAndOtherUSGovernment	0	USD
	us-gaap	Interest Income Securities State And Municipal InterestIncomeSecuritiesStateAndMunicipal	33568000	USD
	us-gaap	Interest Income Securities State And Municipal InterestIncomeSecuritiesStateAndMunicipal	26281000	USD
	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	2928000	USD
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CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	4495000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	4532000	USD
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CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	27841000	USD
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CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	180006000	USD
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CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	1918344000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	2050952000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	2130723000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	599285000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	622381000	USD
CY2021Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2650237000	USD
CY2021Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2753104000	USD
CY2021Q3	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	120000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	120000	USD
CY2021Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	529000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	531000	USD
CY2021Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	139000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	140000	USD
CY2021Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	0	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	0	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	788000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	791000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateNetCarryingAmount	91691000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	97244000	USD
CY2021Q3	us-gaap	Debt Securities Held To Maturity Amortized Cost After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss	92479000	USD
CY2021Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	98035000	USD
CY2021Q3	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	11800000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	11900000	USD
CY2021Q3	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-28000	USD
CY2020Q3	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-232000	USD
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CY2021Q3	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	0	USD
CY2020Q3	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	0	USD
	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	0	USD
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CY2021Q3	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-28000	USD
CY2020Q3	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-232000	USD
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CY2021Q3	sbsi	Other Than Temporarily Impaired Equity Investments OtherThanTemporarilyImpairedEquityInvestments	0	USD
CY2021Q3	sbsi	Federal Home Loan Bank Stock With Other Than Temporary Impairment FederalHomeLoanBankStockWithOtherThanTemporaryImpairment	0	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3647585000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3657779000	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	38022000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	49006000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	3609563000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	3608773000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear	904048000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear	653247000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear	584773000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear	270198000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear	281725000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear	641445000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Revolving FinancingReceivableExcludingAccruedInterestRevolving	312149000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3647585000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear	1030002000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear	779358000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear	370505000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear	389723000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear	199634000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear	627713000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Revolving FinancingReceivableExcludingAccruedInterestRevolving	260844000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3657779000	USD
CY2021Q3	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3647585000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3657779000	USD
CY2021Q3	sbsi	Restructured Nonaccrual Loans RestructuredNonaccrualLoans	1100000	USD
CY2020Q4	sbsi	Restructured Nonaccrual Loans RestructuredNonaccrualLoans	976000	USD
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CY2020Q3	sbsi	Financing Receivable Nonaccrual Interest Income Reversal FinancingReceivableNonaccrualInterestIncomeReversal	0	USD
CY2021Q3	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	1100000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	2200000	USD
CY2021Q3	sbsi	Financing Receivable Collateral Dependent FinancingReceivableCollateralDependent	9100000	USD
CY2020Q4	sbsi	Financing Receivable Collateral Dependent FinancingReceivableCollateralDependent	11500000	USD
CY2021Q3	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	0	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	1200000	USD
CY2021Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	672000	USD
CY2021Q3	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	4	contract
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CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	42913000	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	940000	USD
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CY2020Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	0	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	0	USD
CY2021Q3	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	0	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	437000	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	503000	USD
CY2021Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-4388000	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	38022000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	49006000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	2262000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1525000	USD
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	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-10247000	USD
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	38022000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	59868000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	718000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	361000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	357000	USD
CY2020Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-4401000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	55110000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	24797000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	2259000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	1248000	USD
	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	1011000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	26021000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	55110000	USD
CY2021Q3	us-gaap	Financing Receivable Accrued Interest Before Allowance For Credit Loss FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss	13300000	USD
CY2020Q4	us-gaap	Financing Receivable Accrued Interest Before Allowance For Credit Loss FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss	16400000	USD
CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal In The Next Rolling Twelve Months BorrowedFundsMaturitiesRepaymentsOfPrincipalInTheNextRollingTwelveMonths	676397000	USD
CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal In Rolling Year Two BorrowedFundsMaturitiesRepaymentsOfPrincipalInRollingYearTwo	702000	USD
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CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal In Rolling Year Four BorrowedFundsMaturitiesRepaymentsOfPrincipalInRollingYearFour	764000	USD
CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal In Rolling Year Five BorrowedFundsMaturitiesRepaymentsOfPrincipalInRollingYearFive	582000	USD
CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal In Rolling After Year Five BorrowedFundsMaturitiesRepaymentsOfPrincipalInRollingAfterYearFive	750000	USD
CY2021Q3	sbsi	Borrowed Funds Maturities Repayments Of Principal BorrowedFundsMaturitiesRepaymentsOfPrincipal	679928000	USD
CY2021Q3	sbsi	Line Of Credit Facility Number Of Credit Lines Maintained By Company LineOfCreditFacilityNumberOfCreditLinesMaintainedByCompany	3	credit_line
CY2020Q4	us-gaap	Federal Funds Purchased FederalFundsPurchased	0	USD
CY2021Q3	us-gaap	Federal Funds Purchased FederalFundsPurchased	0	USD
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CY2021Q3	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	20700000	USD
CY2020Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	23200000	USD
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CY2021Q3	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Amount Of Available Unused Funds FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds	1220000000	USD
CY2021Q3	us-gaap	Subordinated Debt SubordinatedDebt	98500000	USD
CY2020Q4	us-gaap	Subordinated Debt SubordinatedDebt	197251000	USD
CY2021Q3	us-gaap	Other Long Term Debt OtherLongTermDebt	60259000	USD
CY2020Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	60255000	USD
CY2021Q3	us-gaap	Long Term Debt LongTermDebt	158759000	USD
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	257506000	USD
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CY2021Q3	us-gaap	Debt Instrument Face Amount DebtInstrumentFaceAmount	605000000	USD
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CY2020Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	39300000	USD
CY2021Q3	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	16350000	USD
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CY2021Q3	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	21380000	USD
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CY2020Q4	us-gaap	Derivative Assets DerivativeAssets	18537000	USD
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CY2021Q3	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	3387000	USD
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CY2021Q3	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	1590000	USD
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CY2021Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	4977000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3783000	USD
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CY2021Q3	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	12500000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	15500000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	USD
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CY2021Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5000000	USD
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CY2021Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.145
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CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3800000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7100000	USD
CY2020Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.123
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.119
CY2021Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	3773000	USD
CY2020Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	6365000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	6386000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1455000	USD
CY2021Q3	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-683000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-345000	USD
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-3296000	USD
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-275000	USD
CY2021Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	3090000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	6020000	USD
CY2021Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	3090000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	6020000	USD
CY2021Q3	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Liability FairValueDisclosureOffbalanceSheetRisksAmountLiability	965070000	USD
CY2020Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Liability FairValueDisclosureOffbalanceSheetRisksAmountLiability	806796000	USD
CY2021Q3	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	240000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	1300000	USD
CY2021Q1	sbsi	Lessee Operating Lease Numberof Contracts LesseeOperatingLeaseNumberofContracts	1	contract
CY2020Q3	sbsi	Reduction Of Right Of Use Asset Obtained In Exchange For Operating Lease Liability ReductionOfRightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	89000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	7900000	USD
CY2020Q2	sbsi	Lessee Operating Lease Numberof Contracts LesseeOperatingLeaseNumberofContracts	1	contract
CY2021Q3	sbsi	Unsettled Trades To Purchase Securities Liability UnsettledTradesToPurchaseSecuritiesLiability	4400000	USD
CY2021Q3	sbsi	Unsettled Trades To Sell Securities UnsettledTradesToSellSecurities	0	USD
CY2020Q4	sbsi	Unsettled Trades To Purchase Securities Liability UnsettledTradesToPurchaseSecuritiesLiability	0	USD
CY2020Q4	sbsi	Unsettled Trades To Sell Securities UnsettledTradesToSellSecurities	0	USD
CY2020Q4	sbsi	Unsettled Issuancesof Brokered C Ds UnsettledIssuancesofBrokeredCDs	0	USD
CY2021Q3	sbsi	Unsettled Issuancesof Brokered C Ds UnsettledIssuancesofBrokeredCDs	0	USD

Files In Submission

Name	View Source	Status
0000705432-21-000177-index-headers.html	Edgar Link	pending
0000705432-21-000177-index.html	Edgar Link	pending
0000705432-21-000177.txt	Edgar Link	pending
0000705432-21-000177-xbrl.zip	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
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report.css	Edgar Link	pending
sbsi-20210930.htm	Edgar Link	pending
sbsi-20210930.xsd	Edgar Link	pending
sbsi-20210930_cal.xml	Edgar Link	unprocessable
sbsi-20210930_def.xml	Edgar Link	unprocessable
sbsi-20210930_htm.xml	Edgar Link	completed
sbsi-20210930_lab.xml	Edgar Link	unprocessable
sbsi-20210930_pre.xml	Edgar Link	unprocessable
sbsi_093021ex311.htm	Edgar Link	pending
sbsi_093021ex312.htm	Edgar Link	pending
sbsi_093021ex32.htm	Edgar Link	pending
Show.js	Edgar Link	pending

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$SBSI
SOUTHSIDE BANCSHARES INC Stock $sbsi

2021 Q4 Form 10-Q Financial Statement

#000070543221000177 Filed on October 29, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SBSI SOUTHSIDE BANCSHARES INC Stock $sbsi

2021 Q4 Form 10-Q Financial Statement

#000070543221000177 Filed on October 29, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SBSI
SOUTHSIDE BANCSHARES INC Stock $sbsi