Commitments and Contingencies Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
FHLB MPF program - remaining outstanding balance of loans sold	$ 26,676	$ 31,552

FHLB MPF Program Remaining Outstanding Balance of Loans Sold

No definition available.

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