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COVERED ASSETS AND FDIC INDEMNIFICATION ASSET (Details 4) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 item | Dec. 31, 2013 | Dec. 31, 2012
Allowance for loan losses disclosures |  |  |  |  |  |
The number of grades used for the loan risk rating system | 8 ewbc_NumberOfGradesOfRiskRatingSystem |  |  |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Provision for (reversal of) loan losses | $ 49,158 us-gaap_ProvisionForLoanAndLeaseLosses |  | $ 22,364 us-gaap_ProvisionForLoanAndLeaseLosses |  | $ 65,184 us-gaap_ProvisionForLoanAndLeaseLosses |
Covered Loans |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 1,604,940 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [1] | 2,461,560 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [2] |  |
Covered Loans | Total |  |  |  |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Beginning balance | 7,745 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 6,647 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Provision for (reversal of) loan losses | 5,033 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 4,028 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 5,016 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Charge-offs | (10,836)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | (1,436)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | (6,510)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Recoveries | 1,563 us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |  |  |
Ending balance | 3,505 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 7,745 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 3,081 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [3] | 5,476 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [4] | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [5]
Acquired with deteriorated credit quality | 424 us-gaap_FinancingReceivableAllowanceForCreditLossesAcquiredWithDeterioratedCreditQuality / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,269 us-gaap_FinancingReceivableAllowanceForCreditLossesAcquiredWithDeterioratedCreditQuality / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | 3,505 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 7,745 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesAndPurchaseCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Covered Loans | Covered Advances |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 253,300 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 320,200 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Beginning balance | 5,476 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [4] | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 6,647 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Provision for (reversal of) loan losses | 6,878 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 1,759 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 5,016 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Charge-offs | (10,836)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | (1,436)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | (6,510)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Recoveries | 1,563 us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |  |  |
Ending balance | 3,081 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [3] | 5,476 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [4] | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 3,081 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [3] | 5,476 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [4] | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Allowance on covered loans | 3,081 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [3] | 5,476 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember | [4] | 5,153 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Covered Loans | PCI Covered Loans |  |  |  |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Beginning balance | 2,269 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |  |  |
Provision for (reversal of) loan losses | (1,845)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,269 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Ending balance | 424 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,269 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Ending balance allocated to: |  |  |  |  |  |
Acquired with deteriorated credit quality | 424 us-gaap_FinancingReceivableAllowanceForCreditLossesAcquiredWithDeterioratedCreditQuality / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,269 us-gaap_FinancingReceivableAllowanceForCreditLossesAcquiredWithDeterioratedCreditQuality / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | 424 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,269 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_PurchasedCreditImpairedCoveredLoansMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
CRE | Covered Loans |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 751,719 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 1,267,363 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
CRE | Covered Loans | Covered Advances |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 59,400 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 46,700 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Ending balance | 676 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 1,800 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,500 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 676 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 1,800 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | 676 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 1,800 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,500 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
C&I | Covered Loans |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 252,986 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 426,621 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
C&I | Covered Loans | Covered Advances |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 154,800 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 230,600 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Ending balance | 2,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 3,200 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,400 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 2,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 3,200 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | 2,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 3,200 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 2,400 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_CommercialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Residential | Covered Loans |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 537,249 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 693,603 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Residential | Covered Loans | Covered Advances |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 11,800 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 12,000 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Ending balance | 166 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 176 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 87 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 166 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 176 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | 166 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 176 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 87 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ResidentialPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Consumer | Covered Loans | Covered Advances |  |  |  |  |  |
Allowance for loan losses disclosures |  |  |  |  |  |
Principal Balance | 27,300 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 30,900 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountCovered / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Financing Receivable Allowance for Credit Losses Roll Forward |  |  |  |  |  |
Ending balance | 223 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 341 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 194 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
Ending balance allocated to: |  |  |  |  |  |
Collectively evaluated for impairment | 223 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | 341 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  |  |
Allowance on covered loans | $ 223 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | $ 341 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |  | $ 194 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ewbc_CoveredAdvancesMember / ewbc_FinancingReceivableInformationByPortfolioSegmentsAxis = us-gaap_ConsumerPortfolioSegmentMember / ewbc_ReceivableByIndemnificationStatusAxis = ewbc_CoveredLoansMember |
[1] | Includes $253.3 million of covered advances comprised of $154.8 million, $59.4 million, $27.3 million and $11.8 million of C&I, CRE, consumer and residential loans, respectively.
[2] | Includes $320.2 million of covered advances comprised of $230.6 million, $46.7 million, $30.9 million and $12.0 million of C&I, CRE, consumer and residential loans, respectively.
[3] | Allowance for loan losses of $2.0 million, $676 thousand, $223 thousand and $166 thousand are allocated to C&I, CRE, consumer and residential loans, respectively.
[4] | Allowance for loan losses of $3.2 million, $1.8 million, $341 thousand and $176 thousand are allocated to C&I, CRE, consumer and residential loans, respectively.
[5] | Allowance for loan losses of $2.4 million, $2.5 million and $194 thousand and $87 thousand are allocated to C&I, CRE, consumer and residential loans, respectively

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