COMMITMENTS AND CONTINGENCIES (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Guarantees
Recourse reserve related to loan sales and securitizations totaled	$ 2.9	$ 3.2
Other Commitments
Other Commitments	84.7	73.1
Loans Sold or Securitized with Recourse
Guarantees
Principal amount of single-family loans with full recourse sold or securitized	39.8	42.2
Principal amount of multifamily loans with limited recourse sold or securitized	273.4	296.6
Principal amount of loans sold or securitized	313.2	338.8
Recourse provision limitation, maximum percentage of the top loss on the multifamily loans	4.00%	4.00%
Recourse reserve related to loan sales and securitizations totaled	2.9	3.2
Commitment to repurchase the loan	0
Loans Sold without Recourse
Guarantees
Principal amount of loans sold or securitized	775.5	818.2
Loans Securitized without Recourse
Guarantees
Principal amount of loans sold or securitized	$ 186.0	$ 193.8

Represents the maximum percentage of the top loss on the multifamily loans with limited recourse.

No definition available.

Name:	ewbc_PercentageLimitOfRecourseOnMultiFamilyLoans
Namespace Prefix:	ewbc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The portion of the allowance for unfunded loan commitments, off-balance sheet credit exposures and recourse provisions specifically related to off-balance sheet loans sold and securitized.

+ References

No definition available.

+ Details

Name:	ewbc_PortionOfAllowanceForUnfundedLoanCommitmentsOffBalanceSheetCreditExposuresAndRecourseProvisionsRelatedToOffBalanceSheetLoansSoldAndSecuritized
Namespace Prefix:	ewbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This is the principal amount outstanding for sold or securitized loans only (across all types of loans).

+ References

No definition available.

+ Details

Name:	ewbc_PrincipalAmountOutstandingOnLoansSoldOrSecuritized
Namespace Prefix:	ewbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the principal amount outstanding of multifamily loans with limited recourse sold or securitized.

+ References

No definition available.

+ Details

Name:	ewbc_PrincipalAmountOutstandingOnMultiFamilyLoansWithLimitedRecourseSoldOrSecuritized
Namespace Prefix:	ewbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the principal amount outstanding of single-family loans with full recourse sold or securitized.

+ References

No definition available.

+ Details

Name:	ewbc_PrincipalAmountOutstandingOnSingleFamilyLoansWithFullRecourseSoldOrSecuritized
Namespace Prefix:	ewbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_OtherCommitmentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration