Disposition of Commercial Property (Details) - Commercial Property in San Francisco $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2017 USD ($) $ / shares
Sale Leaseback Transaction [Line Items]
Sale price	$ 120.6
Pre-tax profit from sale	85.4
Current period gain recognized	71.7
Deferred gain	$ 13.7
Impact from sale on diluted EPS (in dollars per share) \| $ / shares	$ 0.28

Impact of Sale Leaseback on Earnings Per Share, Diluted

No definition available.

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- Definition

Sale Leaseback Transaction, Sale Price

+ References

No definition available.

+ Details

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Namespace Prefix:	ewbc_
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Balance Type:	credit
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- Definition

The portion of the deferred gain that was recognized in the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35688829&loc=d3e50609-112754

+ Details

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Period Type:	duration

- Definition

The amount of the gain recorded in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller to be recognized in future periods.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 25
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6456126&loc=d3e49567-112750

+ Details

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- Definition

The portion of the gain that will be recorded as income or a reduction in rent expense in future periods less amounts recognized in the current period.

+ References

+ Details

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- 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

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- Details

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