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Commitments and Contingencies Other Narratives (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Loss Contingencies [Line Items]
Loan commitments	$ 755,536,000	$ 790,230,000
FHLB MPF program remaining outstanding balance of loans sold	14,411,000	17,032,000
Commitments to extend credit [Member] | Commitments to extend credit, expiration after one year [Member]
Loss Contingencies [Line Items]
Loan commitments	149,250,000
Standby letters of credit [Member]
Loss Contingencies [Line Items]
Loan commitments	13,291,000	10,734,000
Guarantor obligations, current carrying value	$ 0	$ 0

X

- Definition

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

X

- Definition

Unused amount of commitments to extend credit to customers.

+ References

No definition available.

+ Details

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

X

- Definition

Commitments and Contingencies Disclosure [Line Items]

+ References

No definition available.

+ Details

Name:	wtba_CommitmentsAndContingenciesDisclosureLineItems
Namespace Prefix:	wtba_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

FHLB MPF Program Remaining Outstanding Balance of Loans Sold

+ References

No definition available.

+ Details

Name:	wtba_FHLBMPFProgramRemainingOutstandingBalanceofLoansSold
Namespace Prefix:	wtba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=wtba_CommitmentstoextendcreditexpirationafteroneyearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: