- 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

- 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

- 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

- 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

- 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

- References

No definition available.

+ Details

Name:	ewbc_PrinciplesOfConsolidationAbstract
Namespace Prefix:	ewbc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

- Details

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

- Details

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

- Details

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

- Details

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

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	Mar. 31, 2014 entity	Dec. 31, 2016 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 \| trust		6
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