XML 145 R69.htm IDEA: XBRL DOCUMENT
v2.4.1.9

INVESTMENT SECURITIES (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | ---
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | $ 2,619,205 us-gaap_AvailableForSaleSecuritiesAmortizedCost |  | $ 2,786,490 us-gaap_AvailableForSaleSecuritiesAmortizedCost |
Gross Unrealized Gains | 21,128 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax |  | 12,203 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax |
Gross Unrealized Losses | (13,968)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax |  | (64,896)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax |
Fair Value | 2,626,365 us-gaap_AvailableForSaleSecurities |  | 2,733,797 us-gaap_AvailableForSaleSecurities |
U.S. Treasury securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 873,101 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |  | 495,053 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |
Gross Unrealized Gains | 1,971 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |  | 201 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |
Gross Unrealized Losses | (1,637)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |  | (3,622)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |
Fair Value | 873,435 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |  | 491,632 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember |
U.S. government agency and U.S. government sponsored enterprise debt securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 311,927 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |  | 406,807 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |
Gross Unrealized Gains | 490 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |  | 242 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |
Gross Unrealized Losses | (1,393)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |  | (12,726)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |
Fair Value | 311,024 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |  | 394,323 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember |
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 140,957 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 182,257 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Gross Unrealized Gains | 1,056 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 1,062 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Gross Unrealized Losses | (593)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | (4,449)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Fair Value | 141,420 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 178,870 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 785,412 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 892,435 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Gross Unrealized Gains | 9,754 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 7,729 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Gross Unrealized Losses | (4,078)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | (14,927)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Fair Value | 791,088 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |  | 885,237 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember |
Municipal securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 245,408 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 297,390 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |
Gross Unrealized Gains | 6,202 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 1,122 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |
Gross Unrealized Losses | (1,162)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | (17,533)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |
Fair Value | 250,448 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 280,979 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |
Other residential mortgage-backed securities | Investment grade |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 52,694 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | 48,129 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1]
Gross Unrealized Gains | 1,359 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] |  |
Gross Unrealized Losses | (135)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | (1,802)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1]
Fair Value | 53,918 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | 46,327 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1]
Other commercial mortgage-backed securities | Investment grade |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 34,000 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | 51,000 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1]
Gross Unrealized Gains | 53 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | 617 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1]
Fair Value | 34,053 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | 51,617 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1]
Corporate debt securities | Investment grade |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 116,236 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 312,726 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Gross Unrealized Gains |  |  | 613 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Gross Unrealized Losses | (1,054)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | (3,344)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Fair Value | 115,182 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 309,995 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Corporate debt securities | Non-investment grade |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 17,881 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 20,668 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Gross Unrealized Gains |  |  | 62 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Gross Unrealized Losses | (3,200)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | (5,629)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Fair Value | 14,681 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 15,101 us-gaap_AvailableForSaleSecurities / us-gaap_ExternalCreditRatingByGroupingAxis = us-gaap_ExternalCreditRatingNonInvestmentGradeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Other securities |  |  |  |
Schedule of Available-for-sale Securities |  |  |  |
Amortized Cost | 41,589 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |  | 80,025 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |
Gross Unrealized Gains | 243 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |  | 555 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |
Gross Unrealized Losses | (716)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |  | (864)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |
Fair Value | $ 41,116 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |  | $ 79,716 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ewbc_OtherSecuritiesMember |
[1] | Investment securities rated BBB- or higher by S&P, or Baa3 or higher by Moody are considered investment grade. Conversely, investment securities rated below BBB- by S&P, or below Baa3 by Moody are considered non-investment grade.

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=ewbc_CommercialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=ewbc_OtherSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=ewbc_ResidentialMortgageBackedSecuritiesIssuedByUsGovernmentAgenciesAndGovernmentSponsoredEnterpriseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |