v3.25.3

Note 10 - Commitments and Contingent Liabilities (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Unfunded Loan Commitments	$ 164,677	$ 171,672
Guarantor Obligations, Current Carrying Value	1,000	1,000
Other Liabilities [Member]
Reserve for Unfunded Commitments	201	201
Financial Standby Letter of Credit [Member]
Letters of Credit Outstanding, Amount	562	1,926
Commercial Standby Letters of Credit [Member]
Letters of Credit Outstanding, Amount	0	0
Equity Based [Member]
Loan Commitments, Not Unconditionally Cancellable	$ 23,245	$ 26,292

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-15

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-12

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The portion of loan commitments that are not unconditionally cancellable.

+ References

No definition available.

+ Details

Name:	wabc_LoanCommitmentsNotUnconditionallyCancellable
Namespace Prefix:	wabc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of reserve for unfunded commitments.

+ References

No definition available.

+ Details

Name:	wabc_ReserveForUnfundedCommitments
Namespace Prefix:	wabc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the unfunded portion of contractual agreements to lend funds to borrowers.

+ References

No definition available.

+ Details

Name:	wabc_UnfundedLoanCommitments
Namespace Prefix:	wabc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=wabc_CommercialStandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=wabc_EquityBasedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

WESTAMERICA BANCORPORATION 10-Q