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v3.22.2

Current Accounting Developments and Summary of Significant Accounting Policies (Details) $ in Millions | 3 Months Ended
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Mar. 31, 2022 USD ($)
Accounting Policies [Abstract] |
Fair value of debt securities from AFS to HTM | $ 3,010

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- Definition Debt Securities, Available-for-sale, Transfer to Held to Maturity, Amount + References No definition available. + Details
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Namespace Prefix: | ewbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration