XML 59 R143.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Regulatory Requirements and Matters (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Capital adequacy |  |
Tier one common equity for capital adequacy to risk weighted assets | 4.50% |
Tier one risk based capital required for capital adequacy to risk weighted assets | 6.00% |
Capital required for capital adequacy to risk weighted assets | 8.00% |
Fully phased-in capital conservation buffer | 2.50% |
East West Bank |  |
Capital adequacy |  |
Daily average reserve requirement | $ 829.0 | $ 707.3

X
- Definition Represents the daily average reserve requirement as a percentage of the deposits that the entity has to maintain as reserves at the Federal Reserve Bank. + References No definition available. + Details
Name: | ewbc_DailyAverageReserveRequirement
Namespace Prefix: | ewbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Regulatory Capital, Fully Phased-in Capital Conservation Buffer + References No definition available. + Details
Name: | ewbc_RegulatoryCapitalFullyPhasedinCapitalConservationBuffer
Namespace Prefix: | ewbc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Common Equity For Capital Adequacy To Risk Weighted Assets + References No definition available. + Details
Name: | ewbc_TierOneCommonEquityForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | ewbc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=ewbc_EastWestBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |