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Loans and Allowance for Loan Losses Collateral Dep Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	$ 3,004,242	$ 3,008,013
1-4 family residential first mortgages [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	93,122	87,858
Real Estate [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	0	133
Real Estate [Member] | 1-4 family residential first mortgages [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans		133
Equipment
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	0	0
Equipment | 1-4 family residential first mortgages [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans		0
Other Collateral
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	0	0
Other Collateral | 1-4 family residential first mortgages [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans		0
Collateral Pledged
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans	0	133
Allowance for credit Loss allocated to collateral dependent loan	$ 0	0
Collateral Pledged | 1-4 family residential first mortgages [Member]
Loans, Schedule of Collateral Dependent Loans [Line Items]
Loans		133
Allowance for credit Loss allocated to collateral dependent loan		$ 0

X

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Allowance for credit Loss allocated to collateral dependent loan

+ References

No definition available.

+ Details

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Namespace Prefix:	wtba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Financing Receivable, Schedule of Collateral Dependent Loans [Line Items]

+ References

No definition available.

+ Details

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Namespace Prefix:	wtba_
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Balance Type:	na
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- Details

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- Details

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- Details

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X

- Details

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- Details

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