Note 12 - Impact of COVID-19	6 Months Ended
Jun. 30, 2020
Notes to Financial Statements
Unusual or Infrequent Items, or Both, Disclosure [Text Block]	*Note 12:* Impact of COVID-19 The COVID-19 Coronavirus Pandemic Will Have an Uncertain Impact on the Company's Financial Condition and Results of Operations** The COVID-19 coronavirus pandemic caused escalating infections in the United States beginning in the first quarter of 2020 that continued through the second quarter of 2020 and may continue for some time. The spread of the outbreak has disrupted the United States economy including banking and other financial activity in the market areas in which the Company and its banking subsidiary, Westamerica Bank (the "Bank"), operate. Regions and states of the United States of America have implemented varying degrees of "stay at home" directives in an effort to prevent the spread of the virus. On March 19, 2020, the Governor of the State of California ordered all individuals living in the State of California to stay within their residence to prevent the spread of the novel coronavirus and many businesses have suspended or reduced business activities. The California "stay at home" directive excludes essential businesses, including banks, and the Bank remains open and fully operational. These "stay at home" directives have, however, significantly reduced economic activity in the United States and the State of California. In the second quarter of 2020 the “stay at home” directives were gradually lifted in varying stages in counties of the State of California. Counties with high infection rates have delayed reopening and restrictions on certain economic activity remains. California-based initial claims for unemployment have risen considerably during the second quarter of 2020. The Bank's deposits are exclusively sourced within California and its loans are primarily to borrowers domiciled within California. Demand for the Bank's products and services, such as loans and deposits, could be affected as a result of the decline in economic activity within the state. The Bank's investment portfolio contains bonds for which the source of repayment is domestic mortgage repayments, domestic municipalities throughout the United States, and domestic and global corporations. The value of the Bank's investment portfolio may decline if, for example, the general economy deteriorates, inflation increases, credit ratings decline, the issuers’ financial condition deteriorates or the liquidity for debt securities declines. In response to the pandemic, the Federal Reserve has engaged significant levels of monetary policy to provide liquidity and credit facilities to the financial markets. On March 15, 2020, the Federal Open Market Committee ("FOMC") reduced the target range for the federal funds rate to 0 to 0.25 percent; relatedly, the FOMC reduced the interest rate paid on deposit balances to 0.10 percent effective March 16, 2020, all of which may negatively impact net interest income. The Bank maintains deposit balances at the Federal Reserve Bank; the amount that earns interest is identified in the Company's financial statements as "interest-bearing cash". In response to the pandemic, the United States federal government enacted the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act") on March 27, 2020, providing an estimated $2 trillion fiscal stimulus to the United States economy. The CARES Act established the Paycheck Protection Program (PPP) with $350 billion to provide businesses with federally guaranteed loans to support payroll and certain operating expenses. The loans were guaranteed by the United States Small Business Administration (“SBA”) and funded through banks. In April 2020, the PPP program was expanded with an additional $310 billion. At June 30, 2020, the Bank funded $249 million in government guaranteed PPP loans which meaningfully increased interest-earning assets and related interest and fee income. The extent of the spread of the coronavirus, its ultimate containment and its effects on the economy and the Company are uncertain at this time. The effectiveness of the Federal Reserve Bank's monetary policies and the federal government's fiscal policies in stimulating the United States economy is uncertain at this time. Management expects the Company's net interest margin and non-interest income to decline and credit-related losses to increase for an uncertain period given the decline in economic activity occurring due to the coronavirus. The amount of impact on the Company's financial results is uncertain. In addition, the Company's future success and profitability substantially depends upon the skills and experience of its executive officers and directors, many of whom have held positions with the Company for many years. The unanticipated loss or unavailability of key employees due to the outbreak could adversely affect the Company's ability to operate its business or execute its business strategy. Any one or a combination of the factors identified above, or other factors, could materially adversely affect the Company's business, financial condition, results of operations and prospects. *The Recent Decline in Oil Prices Could Have an Impact on the Company's Financial Condition and Results of Operations* Oil prices have declined considerably in the first half of 2020. The decline in oil prices could negatively affect the financial results of industrial sector-based and energy sector-based corporate issuers of corporate bonds owned by the Company. The Company’s corporate debt securities include 14 issuers in industrial and energy sectors with aggregate amortized cost of $275.6 million and fair value of $287.4 million at June 30, 2020. These securities continue to be investment grade rated by a major rating agency. *The Company’s participation in the SBA PPP loan program exposes it to risks* of noncompliance with the PPP and litigation, which could have a material adverse impact on the Company’s business, financial condition and results of operations. The Company is a participating lender in the PPP. The SBA guarantees 100% of loans funded under the PPP. Loan proceeds used for eligible payroll and certain other operating costs are forgiven with repayment of loan principal and accrued interest made by the SBA. There is some ambiguity in the laws, rules and guidance regarding the operation of the PPP, which exposes the Company to potential risks relating to noncompliance with the PPP. Any financial liability, litigation costs or reputational damage caused by PPP related litigation or regulatory enforcement could have a material adverse impact on the Company’s business, financial condition and results of operations. In addition, the Company may be exposed to credit risk on PPP loans if the SBA determines that there is a deficiency in the manner in which the loan was originated, funded, or serviced. If the SBA identifies a deficiency, it could deny its liability under the guaranty, reduce the amount of the guaranty, or, if it has already paid under the guaranty, seek recovery of any loss related to the deficiency from the Company. [The remainder of this page intentionally left blank]

Note 12 - Impact of COVID-19

6 Months Ended

Jun. 30, 2020

Unusual or Infrequent Items, or Both, Disclosure [Text Block]

Note 12: Impact of COVID-19

The COVID-19 Coronavirus Pandemic Will Have an Uncertain Impact on the Company's Financial Condition and Results of Operations

The COVID-19 coronavirus pandemic caused escalating infections in the United States beginning in the first quarter of 2020 that continued through the second quarter of 2020 and may continue for some time. The spread of the outbreak has disrupted the United States economy including banking and other financial activity in the market areas in which the Company and its banking subsidiary, Westamerica Bank (the "Bank"), operate. Regions and states of the United States of America have implemented varying degrees of "stay at home" directives in an effort to prevent the spread of the virus. On March 19, 2020, the Governor of the State of California ordered all individuals living in the State of California to stay within their residence to prevent the spread of the novel coronavirus and many businesses have suspended or reduced business activities. The California "stay at home" directive excludes essential businesses, including banks, and the Bank remains open and fully operational. These "stay at home" directives have, however, significantly reduced economic activity in the United States and the State of California. In the second quarter of 2020 the “stay at home” directives were gradually lifted in varying stages in counties of the State of California. Counties with high infection rates have delayed reopening and restrictions on certain economic activity remains. California-based initial claims for unemployment have risen considerably during the second quarter of 2020.

The Bank's deposits are exclusively sourced within California and its loans are primarily to borrowers domiciled within California. Demand for the Bank's products and services, such as loans and deposits, could be affected as a result of the decline in economic activity within the state.

The Bank's investment portfolio contains bonds for which the source of repayment is domestic mortgage repayments, domestic municipalities throughout the United States, and domestic and global corporations. The value of the Bank's investment portfolio may decline if, for example, the general economy deteriorates, inflation increases, credit ratings decline, the issuers’ financial condition deteriorates or the liquidity for debt securities declines.

In response to the pandemic, the Federal Reserve has engaged significant levels of monetary policy to provide liquidity and credit facilities to the financial markets. On March 15, 2020, the Federal Open Market Committee ("FOMC") reduced the target range for the federal funds rate to 0 to 0.25 percent; relatedly, the FOMC reduced the interest rate paid on deposit balances to 0.10 percent effective March 16, 2020, all of which may negatively impact net interest income. The Bank maintains deposit balances at the Federal Reserve Bank; the amount that earns interest is identified in the Company's financial statements as "interest-bearing cash".

In response to the pandemic, the United States federal government enacted the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act") on March 27, 2020, providing an estimated $2 trillion fiscal stimulus to the United States economy. The CARES Act established the Paycheck Protection Program (PPP) with $350 billion to provide businesses with federally guaranteed loans to support payroll and certain operating expenses. The loans were guaranteed by the United States Small Business Administration (“SBA”) and funded through banks. In April 2020, the PPP program was expanded with an additional $310 billion. At June 30, 2020, the Bank funded $249 million in government guaranteed PPP loans which meaningfully increased interest-earning assets and related interest and fee income.

The extent of the spread of the coronavirus, its ultimate containment and its effects on the economy and the Company are uncertain at this time. The effectiveness of the Federal Reserve Bank's monetary policies and the federal government's fiscal policies in stimulating the United States economy is uncertain at this time.

Management expects the Company's net interest margin and non-interest income to decline and credit-related losses to increase for an uncertain period given the decline in economic activity occurring due to the coronavirus. The amount of impact on the Company's financial results is uncertain.

In addition, the Company's future success and profitability substantially depends upon the skills and experience of its executive officers and directors, many of whom have held positions with the Company for many years. The unanticipated loss or unavailability of key employees due to the outbreak could adversely affect the Company's ability to operate its business or execute its business strategy.

Any one or a combination of the factors identified above, or other factors, could materially adversely affect the Company's business, financial condition, results of operations and prospects.

The Recent Decline in Oil Prices Could Have an Impact on the Company's Financial Condition and Results of Operations

Oil prices have declined considerably in the first half of 2020. The decline in oil prices could negatively affect the financial results of industrial sector-based and energy sector-based corporate issuers of corporate bonds owned by the Company. The Company’s corporate debt securities include 14 issuers in industrial and energy sectors with aggregate amortized cost of $275.6 million and fair value of $287.4 million at June 30, 2020. These securities continue to be investment grade rated by a major rating agency.

The Company’s participation in the SBA PPP loan program exposes it to risks of noncompliance with the PPP and litigation, which could have a material adverse impact on the Company’s business, financial condition and results of operations.

The Company is a participating lender in the PPP. The SBA guarantees 100% of loans funded under the PPP. Loan proceeds used for eligible payroll and certain other operating costs are forgiven with repayment of loan principal and accrued interest made by the SBA. There is some ambiguity in the laws, rules and guidance regarding the operation of the PPP, which exposes the Company to potential risks relating to noncompliance with the PPP. Any financial liability, litigation costs or reputational damage caused by PPP related litigation or regulatory enforcement could have a material adverse impact on the Company’s business, financial condition and results of operations. In addition, the Company may be exposed to credit risk on PPP loans if the SBA determines that there is a deficiency in the manner in which the loan was originated, funded, or serviced. If the SBA identifies a deficiency, it could deny its liability under the guaranty, reduce the amount of the guaranty, or, if it has already paid under the guaranty, seek recovery of any loss related to the deficiency from the Company.

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