$WABC
WESTAMERICA BANCORPORATION Stock $wabc

$wabc Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000117184322001403 Filed on February 28, 2022

Income Statement

Concept	2021 Q4	2021 Q3	2021
Revenue	$43.04M	$43.81M	$173.4M
YoY Change	0.19%	5.91%	4.57%
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	$4.900M	$4.300M	$16.60M
YoY Change	19.51%	-29.51%	-26.55%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense		$492.0K	$1.955M
YoY Change		5.58%	7.18%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$29.47M	$29.90M	$117.0M
YoY Change	-7.61%	11.7%	9.57%
Income Tax	$7.700M	$7.840M	$30.52M
% Of Pretax Income	26.13%	26.22%	26.08%
Net Earnings	$21.72M	$22.06M	$86.51M
YoY Change	-8.88%	10.03%	7.58%
Net Earnings / Revenue	50.46%	50.36%	49.88%
Basic Earnings Per Share	$0.81	$0.82	$3.22
Diluted Earnings Per Share	$0.81	$0.82	$3.22
COMMON SHARES
Basic Shares Outstanding	26.87M	26.87M	26.86M
Diluted Shares Outstanding		26.88M	26.87M

Balance Sheet

Concept	2021 Q4	2021 Q3	2021
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$1.132B	$1.011B
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	$31.16M	$31.60M	$49.10M
YoY Change	-5.05%	-5.48%	-4.84%
Goodwill	$121.7M	$121.7M
YoY Change	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments	$14.20M	$14.20M	$14.20M
YoY Change	0.0%	0.0%	0.0%
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$7.461B	$7.404B	$7.461B
YoY Change	10.57%	12.8%	10.57%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$18.00M	$19.30M	$18.00M
YoY Change	-4.26%	1.05%	-4.26%
Deferred Revenue
YoY Change
Short-Term Debt	$146.2M	$119.1M	$146.2M
YoY Change	42.62%	10.31%	42.63%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$18.00M	$19.30M	$18.00M
YoY Change	-4.26%	1.05%	-4.26%
LONG-TERM LIABILITIES
Long-Term Debt	$0.00	$0.00	$0.00
YoY Change
Other Long-Term Liabilities	$53.20M	$133.7M	$53.20M
YoY Change	-21.76%	169.56%	-21.76%
Total Long-Term Liabilities	$53.20M	$133.7M	$53.20M
YoY Change	-21.76%	169.56%	-21.76%
TOTAL LIABILITIES
Total Short-Term Liabilities	$18.00M	$19.30M	$18.00M
Total Long-Term Liabilities	$53.20M	$133.7M	$53.20M
Total Liabilities	$6.634B	$6.566B	$6.634B
YoY Change	12.38%	14.43%	12.38%
SHAREHOLDERS EQUITY
Retained Earnings	$306.4M	$296.0M
YoY Change	15.9%	16.19%
Common Stock	$471.0M	$470.7M
YoY Change	1.07%	0.74%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$827.1M	$838.0M	$827.1M
YoY Change
Total Liabilities & Shareholders Equity	$7.461B	$7.404B	$7.461B
YoY Change	10.57%	12.8%	10.57%

Cashflow Statement

Concept	2021 Q4	2021 Q3	2021
OPERATING ACTIVITIES
Net Income	$21.72M	$22.06M	$86.51M
YoY Change	-8.88%	10.03%	7.58%
Depreciation, Depletion And Amortization	$4.900M	$4.300M	$16.60M
YoY Change	19.51%	-29.51%	-26.55%
Cash From Operating Activities	$17.60M	$25.60M	$88.74M
YoY Change	53.04%	-15.51%	-17.64%
INVESTING ACTIVITIES
Capital Expenditures	-$200.0K	-$300.0K	$1.324M
YoY Change	-60.0%	0.0%	-39.82%
Acquisitions
YoY Change
Other Investing Activities	-$37.20M	-$184.9M	-$304.8M
YoY Change	-144.39%	-12.62%	-59.18%
Cash From Investing Activities	-$37.40M	-$185.2M	-$306.1M
YoY Change	-144.9%	-12.6%	-59.13%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$232.0K
YoY Change			-98.59%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	140.9M	230.6M	$728.2M
YoY Change	10.51%	189.34%	-18.1%
NET CHANGE
Cash From Operating Activities	17.60M	25.60M	$88.74M
Cash From Investing Activities	-37.40M	-185.2M	-$306.1M
Cash From Financing Activities	140.9M	230.6M	$728.2M
Net Change In Cash	121.1M	71.00M	$510.8M
YoY Change	-45.52%	-169.68%	106.09%
FREE CASH FLOW
Cash From Operating Activities	$17.60M	$25.60M	$88.74M
Capital Expenditures	-$200.0K	-$300.0K	$1.324M
Free Cash Flow	$17.80M	$25.90M	$87.41M
YoY Change	48.33%	-15.36%	-17.18%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2021	dei	Auditor Location AuditorLocation	Sacramento, California
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CY2020Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
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CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	26807000
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.63
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.64
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CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.22
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.98
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.98
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.22
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.98
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.98
CY2021	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.65
CY2020	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.64
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.63
CY2021	us-gaap	Net Income Loss NetIncomeLoss	86509000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	80413000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	80389000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-91891000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	125519000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	93936000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-27167000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	37108000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	27771000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	34000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	71000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	167000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	10000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	21000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	49000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-64748000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	88361000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	66047000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	21761000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	168774000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	146436000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	615591000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	80389000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	66047000	USD
CY2019	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	13699000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	1073000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation Gross StockIssuedDuringPeriodValueShareBasedCompensationGross	1744000	USD
CY2021	us-gaap	Stock Granted During Period Value Sharebased Compensation StockGrantedDuringPeriodValueSharebasedCompensation	106000	USD
CY2019	us-gaap	Stock Granted During Period Value Sharebased Compensation StockGrantedDuringPeriodValueSharebasedCompensation	105000	USD
CY2019	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	488000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	43942000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	731417000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	80413000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	88361000	USD
CY2020	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	2838000	USD
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	534000	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation Gross StockIssuedDuringPeriodValueShareBasedCompensationGross	1875000	USD
CY2020	us-gaap	Stock Granted During Period Value Sharebased Compensation StockGrantedDuringPeriodValueSharebasedCompensation	100000	USD
CY2020	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	16496000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	44285000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	844809000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	86509000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-64748000	USD
CY2021	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	3017000	USD
CY2021	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	526000	USD
CY2021	us-gaap	Stock Issued During Period Value Share Based Compensation Gross StockIssuedDuringPeriodValueShareBasedCompensationGross	1419000	USD
CY2021	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	232000	USD
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	44304000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	827102000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	86509000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	80413000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	80389000	USD
CY2021	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	16617000	USD
CY2020	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	22647000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	20626000	USD
CY2021	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	4300000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2021	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	5576000	USD
CY2020	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	4442000	USD
CY2019	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	260000	USD
CY2021	us-gaap	Stock Option Plan Expense StockOptionPlanExpense	1419000	USD
CY2020	us-gaap	Stock Option Plan Expense StockOptionPlanExpense	1875000	USD
CY2019	us-gaap	Stock Option Plan Expense StockOptionPlanExpense	1744000	USD
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	-0	USD
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	-0	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	433000	USD
CY2021	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	34000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	71000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	217000	USD
CY2021	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	-0	USD
CY2020	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	3536000	USD
CY2019	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	-0	USD
CY2021	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	-0	USD
CY2020	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	71000	USD
CY2019	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	-0	USD
CY2021	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	2499000	USD
CY2020	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	4225000	USD
CY2019	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	2963000	USD
CY2021	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-3899000	USD
CY2020	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	246000	USD
CY2019	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-3662000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3534000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3528000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	14806000	USD
CY2021	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	1054000	USD
CY2020	us-gaap	Proceeds From Repayments Of Debt ProceedsFromRepaymentsOfDebt	71617000	USD
CY2020	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	114000	USD
CY2019	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	307000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-306084000	USD
CY2019	us-gaap	Proceeds From Repayments Of Debt ProceedsFromRepaymentsOfDebt	-20319000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-748922000	USD
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	3017000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-22297000	USD
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	725977000	USD
CY2021	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	0	USD
CY2020	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-353000	USD
CY2019	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	1733000	USD
CY2021	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-72000	USD
CY2020	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-5000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-9000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-6940000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	14280000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-5298000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	88735000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	107744000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	80702000	USD
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-193755000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	126682000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-79396000	USD
CY2021	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	USD
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1273000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1909370000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	2102983000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	970542000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1204455000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1260846000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	631016000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	206400000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	218164000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	238450000	USD
CY2021	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	0	USD
CY2020	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	0	USD
CY2019	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	1797000	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1324000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	2200000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	3994000	USD
CY2021	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	3819000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	875358000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-54218000	USD
CY2021	us-gaap	Proceeds From Repayments Of Debt ProceedsFromRepaymentsOfDebt	43701000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	2838000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	13699000	USD
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	232000	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	16496000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	488000	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	728159000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	889032000	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	44304000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	44285000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	43942000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-105268000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	510810000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	247854000	USD
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	27673000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	26462000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	24491000	USD
CY2021	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	1	pure
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-46863000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	621275000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	373421000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	420284000	USD
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	1132085000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	621275000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	373421000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	5105000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	7697000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	23587000	USD
CY2021	wabc	Right Of Use Asset Obtained In Exchange For Operating Lease Liability Amount Recognized Upon Adoption Of Asu201602 RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAmountRecognizedUponAdoptionOfASU201602	0	USD
CY2020	wabc	Right Of Use Asset Obtained In Exchange For Operating Lease Liability Amount Recognized Upon Adoption Of Asu201602 RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAmountRecognizedUponAdoptionOfASU201602	0	USD
CY2019	wabc	Right Of Use Asset Obtained In Exchange For Operating Lease Liability Amount Recognized Upon Adoption Of Asu201602 RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAmountRecognizedUponAdoptionOfASU201602	15325000	USD
CY2021	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	0	USD
CY2020	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	29000000	USD
CY2019	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	0	USD
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	6309000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	6516000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	5123000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	2027000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	1830000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	1898000	USD
CY2021	us-gaap	Use Of Estimates UseOfEstimates	<p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:justify;margin:0pt;">Accounting Estimates. Certain accounting policies underlying the preparation of these financial statements require Management to make estimates, assumptions, and judgments that affect the amounts reported in the financial statements and accompanying notes. These estimates, assumptions, and judgments are based on information available as of the date of the financial statements; accordingly, as this information changes, the financial statements could reflect different estimates, assumptions, and judgments and as such have a greater possibility of producing results that could be materially different than originally reported. Estimates, assumptions, and judgments are necessary when assets and liabilities are required to be recorded at fair value, when a decline in fair value of an asset <em style="font: inherit;">not</em> carried on the financial statements at fair value warrants an impairment writedown or valuation reserve to be established, or when an asset or liability needs to be recorded contingent upon a future event. The allowance for credit losses accounting is an area requiring the most subjective or complex judgments, and as such could be most subject to revision as new information becomes available. A discussion of the factors affecting the accounting for the allowance for credit losses on loans is included in the following “Loans” and “Allowance for Credit Losses” sections. Carrying assets and liabilities at fair value inherently results in financial statement volatility. The fair values and the information used to record valuation adjustments for certain assets and liabilities are based either on quoted market prices or are provided by other <em style="font: inherit;">third</em> party sources, when available. The “Securities” section discusses the factors that <em style="font: inherit;"> may </em>affect the valuation of the Company’s securities. Although the estimates contemplate current conditions actual results can change.</p> <p style="font-family:'Times New Roman';font-size:10pt;font-variant:normal;margin:0pt;"> </p>
CY2021Q4	us-gaap	Equity Securities Fv Ni Current And Noncurrent EquitySecuritiesFvNiCurrentAndNoncurrent	0	USD
CY2021	wabc	Loans And Leases Receivable Days Before Nonaccrual Status LoansAndLeasesReceivableDaysBeforeNonaccrualStatus	P90D
CY2021	wabc	Loans And Leases Receivable Certain Consumer Loans And Auto Receivables Days Before Chargeoff LoansAndLeasesReceivableCertainConsumerLoansAndAutoReceivablesDaysBeforeChargeoff	P120D
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	3900751000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	163576000	USD
CY2020Q1	wabc	Allowance For Credit Losses For Unfunded Commitments AllowanceForCreditLossesForUnfundedCommitments	19484000	USD
CY2020Q1	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2020Q1	wabc	Reserve For Unfunded Commitments ReserveForUnfundedCommitments	2160000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	7000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	9000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	4568346000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	80924000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	10415000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4638855000	USD
CY2021Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	306403000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	6196000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	37000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	312562000	USD
CY2021Q4	wabc	Debt Securities Availableforsale And Heldtomaturity Amortized Cost DebtSecuritiesAvailableforsaleAndHeldtomaturityAmortizedCost	4874749000	USD
CY2021Q4	wabc	Debt Securities Gross Unrecognized Gains DebtSecuritiesGrossUnrecognizedGains	87120000	USD
CY2021Q4	wabc	Debt Securities Gross Unrecognized Losses DebtSecuritiesGrossUnrecognizedLosses	10452000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale And Held To Maturity DebtSecuritiesAvailableForSaleAndHeldToMaturity	4951417000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	1142000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4063185000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	515598000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	14121000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	32000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	529687000	USD
CY2020Q4	wabc	Debt Securities Availableforsale And Heldtomaturity Amortized Cost DebtSecuritiesAvailableforsaleAndHeldtomaturityAmortizedCost	4416349000	USD
CY2020Q4	wabc	Debt Securities Gross Unrecognized Gains DebtSecuritiesGrossUnrecognizedGains	177697000	USD
CY2020Q4	wabc	Debt Securities Gross Unrecognized Losses DebtSecuritiesGrossUnrecognizedLosses	1174000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale And Held To Maturity DebtSecuritiesAvailableForSaleAndHeldToMaturity	4592872000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	630174000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	922170000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	652952000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	4227129000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	158013000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	161095000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	399997000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	411726000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateNetCarryingAmount	148390000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	151467000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	4568346000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4638855000	USD
CY2021Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	306403000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	312562000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	212140000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	213715000	USD
CY2020Q4	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	54526000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	54927000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	306333000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	309257000	USD
CY2021Q4	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	15836000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	15941000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	707062000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	738057000	USD
CY2021Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	125001000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	127539000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	2320559000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2347242000	USD
CY2021Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	17176000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	17615000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	834395000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	832573000	USD
CY2021Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	0	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	0	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	4168349000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	974438000	USD
CY2020Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	129786000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	133195000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	1767747000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	1851184000	USD
CY2020Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	89610000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	93043000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	368520000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	370896000	USD
CY2020Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	3270577000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	3410233000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	273922000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	281165000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateNetCarryingAmount	241676000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Without Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	248522000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	3900751000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	4063185000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	9000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	515598000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	529687000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	88	pure
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	911513000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	10215000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	13	pure
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	52358000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	200000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	101	pure
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	963871000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	10415000	USD
CY2021Q4	wabc	Heldtomaturity Securities Less Than12 Months Number Of Positions HeldtomaturitySecuritiesLessThan12MonthsNumberOfPositions	1	pure
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	542000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	19000	USD
CY2021Q4	wabc	Heldtomaturity Securities12 Months Or Longer Number Of Positions HeldtomaturitySecurities12MonthsOrLongerNumberOfPositions	3	pure
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	530000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	18000	USD
CY2021Q4	wabc	Heldtomaturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 HeldtomaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	4	pure
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	1072000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	37000	USD
CY2021Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	1021566000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	888577000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	40	pure
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	269526000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1100000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	2	pure
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	14980000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	42000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	42	pure
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	284506000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	1142000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	9000	USD
CY2019Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	-2000	USD
CY2020	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	-7000	USD
CY2021	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Writeoff DebtSecuritiesHeldToMaturityAllowanceForCreditLossWriteoff	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Writeoff DebtSecuritiesHeldToMaturityAllowanceForCreditLossWriteoff	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Recovery DebtSecuritiesHeldToMaturityAllowanceForCreditLossRecovery	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Recovery DebtSecuritiesHeldToMaturityAllowanceForCreditLossRecovery	0	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	7000	USD
CY2021Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1068126000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	23854000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	2000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	3248000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2906000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	23514000	USD
CY2021Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	306403000	USD
CY2021	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	106329000	USD
CY2020	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	93163000	USD
CY2019	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	77800000	USD
CY2021	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	8424000	USD
CY2020	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	12151000	USD
CY2019	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	15736000	USD
CY2021	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	114753000	USD
CY2020	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	105314000	USD
CY2019	us-gaap	Interest And Dividend Income Securities InterestAndDividendIncomeSecurities	93536000	USD
CY2021Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1068126000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1256243000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	19484000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	4307000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	4199000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2245000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	23854000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	21351000	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	4570000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2703000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	19484000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1256243000	USD
CY2021Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	692000	USD
CY2021Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1068126000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	4329000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1256243000	USD
CY2021Q4	wabc	Loans And Leases Receivable Nonaccrual Commitment To Lend LoansAndLeasesReceivableNonaccrualCommitmentToLend	0	USD
CY2019	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	16075000	USD
CY2019	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	283000	USD
CY2021	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	3	pure
CY2021	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	3026000	USD
CY2021Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	1965000	USD
CY2021Q4	wabc	Financing Receivable Modifications Period End Impairment Allowance FinancingReceivableModificationsPeriodEndImpairmentAllowance	0	USD
CY2020	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	7	pure
CY2020	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	8608000	USD
CY2020Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	6221000	USD
CY2020Q4	wabc	Financing Receivable Modifications Period End Impairment Allowance FinancingReceivableModificationsPeriodEndImpairmentAllowance	0	USD
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	pure
CY2020Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	USD
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CY2021Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	247000	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	346000	USD
CY2021Q4	wabc	Unsecured Loan Limit Percentage Of Shareholders Equity California Financial Code UnsecuredLoanLimitPercentageOfShareholdersEquityCaliforniaFinancialCode	0.15	pure
CY2021Q4	wabc	Secured And Unsecured Loan Limit Percentage California Financial Code SecuredAndUnsecuredLoanLimitPercentageCaliforniaFinancialCode	0.25	pure
CY2021Q4	wabc	Loan Commitments Related To Real Estate Loans LoanCommitmentsRelatedToRealEstateLoans	34226000	USD
CY2020Q4	wabc	Loan Commitments Related To Real Estate Loans LoanCommitmentsRelatedToRealEstateLoans	37456000	USD
CY2020Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	14227000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	88671000	USD
CY2021Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	57516000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	31155000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	87584000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	54771000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	32813000	USD
CY2021	us-gaap	Depreciation And Amortization DepreciationAndAmortization	2978000	USD
CY2020	us-gaap	Depreciation And Amortization DepreciationAndAmortization	3683000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	3879000	USD
CY2021Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	14069000	USD
CY2020Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	14069000	USD
CY2021Q4	us-gaap	Other Investments And Securities At Cost OtherInvestmentsAndSecuritiesAtCost	158000	USD
CY2020Q4	us-gaap	Other Investments And Securities At Cost OtherInvestmentsAndSecuritiesAtCost	158000	USD
CY2021Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	14227000	USD
CY2021Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	63107000	USD
CY2020Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	60444000	USD
CY2021Q4	wabc	Lihtc Investments LIHTCInvestments	37145000	USD
CY2020Q4	wabc	Lihtc Investments LIHTCInvestments	18335000	USD
CY2021Q4	us-gaap	Interest Receivable Current InterestReceivableCurrent	35521000	USD
CY2020Q4	us-gaap	Interest Receivable Current InterestReceivableCurrent	33022000	USD
CY2021Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	4757000	USD
CY2020Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	4572000	USD
CY2021Q4	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	12678000	USD
CY2020Q4	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	10471000	USD
CY2021Q4	us-gaap	Other Assets OtherAssets	185415000	USD
CY2020Q4	us-gaap	Other Assets OtherAssets	159903000	USD
CY2021Q4	wabc	Lihtc Investments LIHTCInvestments	37145000	USD
CY2021Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	26485000	USD
CY2020Q4	wabc	Lihtc Investments LIHTCInvestments	18335000	USD
CY2020Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	12202000	USD
CY2021Q4	us-gaap	Qualified Affordable Housing Project Investments Commitment QualifiedAffordableHousingProjectInvestmentsCommitment	26485000	USD
CY2020Q4	us-gaap	Other Liabilities OtherLiabilities	112598000	USD
CY2021	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	-2620000	USD
CY2020	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	-2440000	USD
CY2019	us-gaap	Income Loss From Affordable Housing Projects Equity Method Investments IncomeLossFromAffordableHousingProjectsEquityMethodInvestments	-2400000	USD
CY2021	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	2300000	USD
CY2020	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	900000	USD
CY2019	us-gaap	Affordable Housing Tax Credits And Other Tax Benefits Amount AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount	875000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	2501000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	25778000	USD
CY2021Q4	wabc	Securities Purchases Pending Settlement SecuritiesPurchasesPendingSettlement	0	USD
CY2020Q4	wabc	Securities Purchases Pending Settlement SecuritiesPurchasesPendingSettlement	29000000	USD
CY2021Q4	wabc	Other Liabilities Excluding Operating Lease Liability OtherLiabilitiesExcludingOperatingLeaseLiability	53241000	USD
CY2020Q4	wabc	Other Liabilities Excluding Operating Lease Liability OtherLiabilitiesExcludingOperatingLeaseLiability	38988000	USD
CY2021Q4	us-gaap	Other Liabilities OtherLiabilities	73722000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P4Y2M12D
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0167	pure
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	5698000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	4984000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	3393000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	2201000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	786000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	1478000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	18540000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	560000	USD
CY2021	wabc	Amortization Expense Adjustment Resulting From A Change In Estimates Of Useful Lives Or Residual Values AmortizationExpenseAdjustmentResultingFromAChangeInEstimatesOfUsefulLivesOrResidualValues	0	USD
CY2021Q4	us-gaap	Goodwill Goodwill	121673000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	121673000	USD
CY2020Q4	us-gaap	Noninterest Bearing Deposit Liabilities Domestic NoninterestBearingDepositLiabilitiesDomestic	2725177000	USD
CY2021Q4	us-gaap	Demand Deposit Accounts DemandDepositAccounts	1260869000	USD
CY2020Q4	us-gaap	Demand Deposit Accounts DemandDepositAccounts	1102601000	USD
CY2021Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1940395000	USD
CY2020Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1703812000	USD
CY2021Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	72527000	USD
CY2020Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	79825000	USD
CY2021Q4	wabc	Time Deposits100 Thousand Through250 Thousand TimeDeposits100ThousandThrough250Thousand	47666000	USD
CY2020Q4	wabc	Time Deposits100 Thousand Through250 Thousand TimeDeposits100ThousandThrough250Thousand	49323000	USD
CY2021Q4	wabc	Time Deposits More Than250 Thousand TimeDepositsMoreThan250Thousand	23419000	USD
CY2020Q4	wabc	Time Deposits More Than250 Thousand TimeDepositsMoreThan250Thousand	27241000	USD
CY2021Q4	us-gaap	Deposits Deposits	6413956000	USD
CY2020Q4	us-gaap	Deposits Deposits	5687979000	USD
CY2021Q4	wabc	Demand Deposit Overdrafts DemandDepositOverdrafts	611000	USD
CY2020Q4	wabc	Demand Deposit Overdrafts DemandDepositOverdrafts	682000	USD
CY2021	us-gaap	Interest Expense Time Deposits100000 Or More InterestExpenseTimeDeposits100000OrMore	265000	USD
CY2020	us-gaap	Interest Expense Time Deposits100000 Or More InterestExpenseTimeDeposits100000OrMore	319000	USD
CY2019	us-gaap	Interest Expense Time Deposits100000 Or More InterestExpenseTimeDeposits100000OrMore	326000	USD
CY2021Q4	us-gaap	Noninterest Bearing Deposit Liabilities Domestic NoninterestBearingDepositLiabilitiesDomestic	3069080000	USD
CY2021	us-gaap	Schedule Of Repurchase Agreements ScheduleOfRepurchaseAgreements	<table border="0" cellpadding="0" cellspacing="0" class="finTable" style="width: 100%; font-size: 10pt; font-family: Times New Roman; text-indent: 0px;"> <tbody> <tr style="vertical-align: bottom;"> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="6" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">Repurchase Agreements (Sweep)<br/> Accounted for as Secured Borrowings</p> </td> <td style="font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> </tr> <tr style="vertical-align: bottom;"> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="6" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">Remaining Contractual Maturity of the Agreements</p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> </tr> <tr style="vertical-align: bottom;"> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="6" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">Overnight and Continuous</p> </td> <td style="font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> </tr> <tr style="vertical-align: bottom;"> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="2" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">At December 31,</p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="2" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">At December 31,</p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> </tr> <tr style="vertical-align: bottom;"> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="2" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">2021</p> </td> <td style="font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="2" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;">2020</p> </td> <td style="font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(204, 238, 255);"> <td style="font-family: Times New Roman; font-size: 10pt; width: 70%;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt;">Repurchase agreements:</p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td colspan="6" style="text-align: center; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> <p style="font-family:Times New Roman;font-size:10pt;font-variant:normal;text-align:center;margin:0pt;"><em style="font: inherit;"><em style="font: inherit;">(In thousands)</em></em></p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(255, 255, 255);"> <td style="font-family: Times New Roman; font-size: 10pt;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt; margin-left: 18pt; text-indent: -9pt;">Collateral securing borrowings:</p> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> <td style="font-family: Times New Roman; font-size: 10pt;"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(204, 238, 255);"> <td style="font-family: Times New Roman; font-size: 10pt;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt; margin-left: 27pt; text-indent: -9pt;">Agency residential MBS</p> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">42,295</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">67,019</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(255, 255, 255);"> <td style="font-family: Times New Roman; font-size: 10pt;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt; margin-left: 27pt; text-indent: -9pt;">Corporate securities</p> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; padding-bottom: 1px;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> <td style="width: 12%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; text-align: right; border-bottom: 1px solid rgb(0, 0, 0);">254,005</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; padding-bottom: 1px;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> <td style="width: 12%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; text-align: right; border-bottom: 1px solid rgb(0, 0, 0);">188,195</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 1px solid rgb(0, 0, 0);"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(204, 238, 255);"> <td style="font-family: Times New Roman; font-size: 10pt;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt; margin-left: 36pt; text-indent: -9pt;">Total collateral carrying value</p> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 3px double rgb(0, 0, 0);">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 3px double rgb(0, 0, 0);">296,300</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; border-bottom: 3px double rgb(0, 0, 0); margin-left: 0pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 3px double rgb(0, 0, 0);">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt; border-bottom: 3px double rgb(0, 0, 0);">255,214</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; border-bottom: 3px double rgb(0, 0, 0); margin-left: 0pt;"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(255, 255, 255);"> <td style="font-family: Times New Roman; font-size: 10pt;"> <p style="font-family: Times New Roman; font-size: 10pt; font-variant: normal; margin-top: 0pt; margin-bottom: 0pt;">Total short-term borrowed funds</p> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">146,246</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt;"> </td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">$</td> <td style="width: 12%; text-align: right; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;">102,545</td> <td style="width: 1%; font-family: Times New Roman; font-size: 10pt; margin-left: 0pt;"> </td> </tr> </tbody> </table>
CY2021Q4	us-gaap	Carrying Value Of Securities Sold Under Repurchase Agreements And Deposits Received For Securities Loaned CarryingValueOfSecuritiesSoldUnderRepurchaseAgreementsAndDepositsReceivedForSecuritiesLoaned	296300000	USD
CY2020Q4	us-gaap	Carrying Value Of Securities Sold Under Repurchase Agreements And Deposits Received For Securities Loaned CarryingValueOfSecuritiesSoldUnderRepurchaseAgreementsAndDepositsReceivedForSecuritiesLoaned	255214000	USD
CY2021Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	146246000	USD
CY2020Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	102545000	USD
CY2021Q4	us-gaap	Share Price SharePrice	57.73
CY2021	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Lower Range Limit ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit	40
CY2021	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Upper Range Limit ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit	70
CY2021Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Outstanding Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions	793000
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	755000	USD
CY2021	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Remaining Contractual Term2 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2	P7Y1M6D
CY2021Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Exercise Price Beginning Balance1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	60
CY2021Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Exercisable Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions	446000
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	640000	USD
CY2021	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Remaining Contractual Term2 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2	P6Y1M6D
CY2021Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Exercise Price1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	60
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	193000
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	184000
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	250000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.20	pure
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.20	pure
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.20	pure
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P4Y8M12D
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P3Y6M
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P4Y8M12D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0046	pure
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0152	pure
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0267	pure
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0279	pure
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0259	pure
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0255	pure
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	7.50
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.64
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	10.19
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	53000
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	56.82
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	693000
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	61.25
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	193000
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	57.08
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	60.48
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	446000
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	60.07
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	40000
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P6Y1M6D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	62.14
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	793000
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P7Y1M6D
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	185000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	9.61
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares	34000
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	373000
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	9.39
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	193000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	7.50
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	8.42
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	347000
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	8.31
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	7.50
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.64
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	10.19
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	2494000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	454000	USD
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	693000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	3398000	USD
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	1783000	USD
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	1735000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	1980000	USD
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	53000
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	52000
CY2020	wabc	Excess Tax Deduction Exceeding Related Sharebased Compensation Operating Activities ExcessTaxDeductionExceedingRelatedSharebasedCompensationOperatingActivities	295000	USD
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	516000
CY2019	wabc	Excess Tax Deduction Exceeding Related Sharebased Compensation Operating Activities ExcessTaxDeductionExceedingRelatedSharebasedCompensationOperatingActivities	1485000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	28000
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	27000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	13000
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	10000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	9000
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	9000
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	2000
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-0
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	30000
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	28000
CY2009Q1	us-gaap	Class Of Warrant Or Right Number Of Securities Called By Warrants Or Rights ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights	246640
CY2009Q1	us-gaap	Class Of Warrant Or Right Exercise Price Of Warrants Or Rights1 ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1	50.92
CY2019Q1	wabc	Stock Issued During Period Shares Warrants Exercised StockIssuedDuringPeriodSharesWarrantsExercised	50788
CY2021Q4	us-gaap	Stock Repurchase Program Remaining Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased	1750000
CY2021Q4	wabc	Additional Classes Of Stock Authorized AdditionalClassesOfStockAuthorized	2	pure
CY2021Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	150000000
CY2021Q4	wabc	Capital Conservation Buffer CapitalConservationBuffer	0.025	pure
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	2792000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	2353000	USD
CY2020Q4	wabc	Deferred Tax Assets Limited Partnership Investments DeferredTaxAssetsLimitedPartnershipInvestments	1066000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Impairment Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses	2673000	USD
CY2021Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	653026000	USD
CY2021Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1493	pure
CY2021Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	306277000	USD
CY2021Q4	wabc	Common Equity Tier1 Capital Required For Capital Adequacy To Risk Weighted Assets CommonEquityTier1CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0700	pure
CY2021Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	653026000	USD
CY2021Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1493	pure
CY2021Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	371908000	USD
CY2021Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0850	pure
CY2021Q4	us-gaap	Capital Capital	676749000	USD
CY2021Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1547	pure
CY2021Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	459416000	USD
CY2021Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.1050	pure
CY2021Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	653026000	USD
CY2021Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0906	pure
CY2021Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	288423000	USD
CY2021Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400	pure
CY2020Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	604833000	USD
CY2020Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1604	pure
CY2020Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	263903000	USD
CY2020Q4	wabc	Common Equity Tier1 Capital Required For Capital Adequacy To Risk Weighted Assets CommonEquityTier1CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0700	pure
CY2020Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	604833000	USD
CY2020Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1604	pure
CY2020Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	320454000	USD
CY2020Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0850	pure
CY2020Q4	us-gaap	Capital Capital	628797000	USD
CY2020Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1668	pure
CY2020Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	395855000	USD
CY2020Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.1050	pure
CY2020Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	604833000	USD
CY2020Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0940	pure
CY2020Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	257488000	USD
CY2020Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400	pure
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	6852000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	6789000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	2518000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	2262000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	4524000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	4789000	USD
CY2021Q4	wabc	Deferred Tax Assets Purchased Assets And Assumed Liabilities DeferredTaxAssetsPurchasedAssetsAndAssumedLiabilities	475000	USD
CY2020Q4	wabc	Deferred Tax Assets Purchased Assets And Assumed Liabilities DeferredTaxAssetsPurchasedAssetsAndAssumedLiabilities	552000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	445000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	480000	USD
CY2021Q4	wabc	Deferred Tax Assets Visa Class B Shares DeferredTaxAssetsVISAClassBShares	348000	USD
CY2020Q4	wabc	Deferred Tax Assets Visa Class B Shares DeferredTaxAssetsVISAClassBShares	284000	USD
CY2021Q4	wabc	Deferred Tax Assets Limited Partnership Investments DeferredTaxAssetsLimitedPartnershipInvestments	0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Impairment Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses	2429000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	748000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	416000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	585000	USD
CY2021Q4	wabc	Deferred Tax Assets Lease Liability DeferredTaxAssetsLeaseLiability	5263000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	1001000	USD
CY2020Q4	wabc	Deferred Tax Assets Lease Liability DeferredTaxAssetsLeaseLiability	5513000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	103000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	800000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	27742000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	28318000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	1776000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	-0	USD
CY2021Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	25966000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	28318000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	196000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Financing Costs DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts	106000	USD
CY2021Q4	wabc	Deferred Tax Liabilities Unrealized Gain On Availableforsale Securities Gross DeferredTaxLiabilitiesUnrealizedGainOnAvailableforsaleSecuritiesGross	20845000	USD
CY2020Q4	wabc	Deferred Tax Liabilities Unrealized Gain On Availableforsale Securities Gross DeferredTaxLiabilitiesUnrealizedGainOnAvailableforsaleSecuritiesGross	48021000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	5263000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	5513000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	459000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	456000	USD
CY2021Q4	wabc	Deferred Tax Liabilities Limited Partnership Investments DeferredTaxLiabilitiesLimitedPartnershipInvestments	1704000	USD
CY2020Q4	wabc	Deferred Tax Liabilities Limited Partnership Investments DeferredTaxLiabilitiesLimitedPartnershipInvestments	0	USD
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	28467000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	54096000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	2501000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	25778000	USD
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	15299000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	15982000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	11570000	USD
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	11320000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	10654000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	9595000	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	26619000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	26636000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	21165000	USD
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1281000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-538000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	2411000	USD
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	842000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	292000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	982000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2123000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-246000	USD
CY2019	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-269000	USD
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CY2021	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-1776000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3393000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	30518000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26390000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	24827000	USD
CY2021	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	24576000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	22429000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	22095000	USD
CY2021	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	2070000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	2808000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	3584000	USD
CY2021	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	9757000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8647000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8625000	USD
CY2021	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-1776000	USD
CY2020	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-0	USD
CY2019	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-269000	USD
CY2021	wabc	Income Tax Rate Reconciliation Deduction Stock Compensation IncomeTaxRateReconciliationDeductionStockCompensation	-0	USD
CY2020	wabc	Income Tax Rate Reconciliation Deduction Stock Compensation IncomeTaxRateReconciliationDeductionStockCompensation	62000	USD
CY2019	wabc	Income Tax Rate Reconciliation Deduction Stock Compensation IncomeTaxRateReconciliationDeductionStockCompensation	312000	USD
CY2021	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	2621000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	1061000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	1040000	USD
CY2021	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	48000	USD
CY2020	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	44000	USD
CY2019	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	38000	USD
CY2021	wabc	Income Tax Reconciliation Cash Value Life Insurance IncomeTaxReconciliationCashValueLifeInsurance	389000	USD
CY2020	wabc	Income Tax Reconciliation Cash Value Life Insurance IncomeTaxReconciliationCashValueLifeInsurance	383000	USD
CY2019	wabc	Income Tax Reconciliation Cash Value Life Insurance IncomeTaxReconciliationCashValueLifeInsurance	464000	USD
CY2021	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-463000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-328000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-724000	USD
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CY2020	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	52000	USD
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CY2019	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	146000	USD
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CY2019Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	1782000	USD
CY2021Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	0	USD
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CY2020Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.0180	pure
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CY2021Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	534000	USD
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CY2021	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	0	USD
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CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	499000	USD
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CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	27006000
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CY2021Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	0	USD
CY2021Q1	us-gaap	Noninterest Income NoninterestIncome	10189000	USD
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CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	22063000	USD
CY2021Q4	us-gaap	Net Income Loss NetIncomeLoss	21720000	USD
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CY2020Q4	us-gaap	Noninterest Income NoninterestIncome	13959000	USD
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CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	24603000	USD
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CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	23838000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.63
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CY2019Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	39483000	USD
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CY2019Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	39427000	USD
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CY2019Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	0	USD
CY2019Q1	us-gaap	Noninterest Income NoninterestIncome	11579000	USD
CY2019Q2	us-gaap	Noninterest Income NoninterestIncome	12288000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	11809000	USD
CY2019Q4	us-gaap	Noninterest Income NoninterestIncome	11732000	USD
CY2019Q1	us-gaap	Noninterest Expense NoninterestExpense	25183000	USD
CY2019Q2	us-gaap	Noninterest Expense NoninterestExpense	25561000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	24033000	USD
CY2019Q4	us-gaap	Noninterest Expense NoninterestExpense	24209000	USD
CY2019Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	25385000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	25866000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	27016000	USD
CY2019Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	26950000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	19646000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	19625000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	20390000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	20728000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.73
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.73
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.76
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.73
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.73
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2019Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.40
CY2019Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.41
CY2019Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.41
CY2019Q4	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.41

Files In Submission

Name	View Source	Status
0001171843-22-001403-index-headers.html	Edgar Link	pending
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wabc-20211231_cal.xml	Edgar Link	unprocessable
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wabc20211231_10k.htm	Edgar Link	pending
wabc20211231_10k_htm.xml	Edgar Link	completed

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$WABC
WESTAMERICA BANCORPORATION Stock $wabc

2021 Q4 Form 10-K Financial Statement

#000117184322001403 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WABC WESTAMERICA BANCORPORATION Stock $wabc

2021 Q4 Form 10-K Financial Statement

#000117184322001403 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WABC
WESTAMERICA BANCORPORATION Stock $wabc