XML 72 R53.htm IDEA: XBRL DOCUMENT
v3.3.1.900

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2014 entity | Dec. 31, 2015 location trust banking_branch representative_office
Operations summary |  |
Number of banking locations | location |  | 130
Principles of Consolidation |  |
Number of wholly owned subsidiaries that are statutory business trusts ("the Trusts") | trust |  | 6
Loans held-for-investments, net |  |
Number of past due days for the loans receivable to be placed on nonaccrual status |  | 90 days
MetroCorp |  |
Principles of Consolidation |  |
Number of acquisitions | entity | 1 |
Greater China |  |
Operations summary |  |
Number of full-service branches |  | 5
Number of representative offices | representative_office |  | 5
Shanghai |  |
Operations summary |  |
Number of full-service branches |  | 2
Shanghai Pilot Free Trade Zone |  |
Operations summary |  |
Number of full-service branches |  | 1

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: | dei_EntityLocationLineItems
Namespace Prefix: | dei_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of past due days for the loans receivable to be placed on nonaccrual status. + References No definition available. + Details
Name: | ewbc_LoansReceivableNonAccrualStatusNumberOfPastDueDays
Namespace Prefix: | ewbc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of banking locations in which the entity operates. + References No definition available. + Details
Name: | ewbc_NumberOfBankingLocations
Namespace Prefix: | ewbc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of full-service branches of the entity. + References No definition available. + Details
Name: | ewbc_NumberOfFullServiceBranches
Namespace Prefix: | ewbc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of representative offices of the entity. + References No definition available. + Details
Name: | ewbc_NumberOfRepresentativeOffices
Namespace Prefix: | ewbc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of wholly owned subsidiaries of the entity that are statutory business trusts, which are not consolidated. + References No definition available. + Details
Name: | ewbc_NumberOfWhollyOwnedStatutoryBusinessTrusts
Namespace Prefix: | ewbc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | ewbc_PrinciplesOfConsolidationAbstract
Namespace Prefix: | ewbc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition The number of businesses acquired by the entity during the period. + References No definition available. + Details
Name: | us-gaap_NumberOfBusinessesAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=ewbc_MetroCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_CN
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=ewbc_ShanghaiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=ewbc_ShanghaiPilotFreeTradeZoneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |