v3.26.1
Summary of Significant Accounting Policies - Additional Information (Detail)
6 Months Ended
Jun. 30, 2026
Subsidiary
Accounting Policies [Abstract]
Number of unconsolidated subsidiaries
8
X
- References
No definition available.
+ Details
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us-gaap_AccountingPoliciesAbstract
Namespace Prefix:
us-gaap_
Data Type:
xbrli:stringItemType
Balance Type:
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Period Type:
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X
- Definition
Number of unconsolidated subsidiaries.
+ References
No definition available.
+ Details
Name:
wal_NumberOfUnconsolidatedSubsidiaries
Namespace Prefix:
wal_
Data Type:
xbrli:integerItemType
Balance Type:
na
Period Type:
duration