CUSTOMER DEPOSIT ACCOUNTS (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Customer deposit account balances
Noninterest-bearing demand	$ 7,381,030,000	$ 5,821,899,000
Interest-bearing checking	2,545,618,000ewbc_InterestBearingDepositChecking	1,749,479,000ewbc_InterestBearingDepositChecking
Money market accounts	6,318,120,000us-gaap_DepositsMoneyMarketDeposits	5,653,412,000us-gaap_DepositsMoneyMarketDeposits
Savings deposits	1,651,267,000us-gaap_DepositsSavingsDeposits	1,363,780,000us-gaap_DepositsSavingsDeposits
Total core deposits	17,896,035,000ewbc_CoreDeposits	14,588,570,000ewbc_CoreDeposits
Time deposits:
Less than $100,000	1,662,046,000us-gaap_TimeDepositsLessThan100000	1,678,850,000us-gaap_TimeDepositsLessThan100000
$100,000 or greater	4,450,693,000us-gaap_TimeDeposits100000OrMore	4,145,498,000us-gaap_TimeDeposits100000OrMore
Total time deposits	6,112,739,000us-gaap_TimeDeposits	5,824,348,000us-gaap_TimeDeposits
Total deposits	24,008,774,000us-gaap_Deposits	20,412,918,000us-gaap_Deposits
Time deposits $100 thousand or greater held by the Company's foreign branch located in Hong Kong	$ 133,300,000us-gaap_TimeDeposits100000OrMoreForeign	$ 169,700,000us-gaap_TimeDeposits100000OrMoreForeign

The aggregate of all deposit liabilities held by the entity excluding time deposits.

No definition available.

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- Definition

Amount of interest-bearing checking deposit liabilities.

+ References

No definition available.

+ Details

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- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

+ Details

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- Definition

Amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.

+ References

+ Details

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- Definition

Amount of interest bearing deposits with no stated maturity, which may include passbook and statement savings accounts and money-market deposit accounts (MMDAs).

+ References

+ Details

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- Definition

The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

+ References

+ Details

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- Definition

Amount of deposits that cannot be withdrawn before a set date without penalty or for which notice of withdrawal is required. Time deposits include, but are not limited to, certificates of deposits, individual retirement accounts and open accounts.

+ References

+ Details

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- Definition

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

+ References

+ Details

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- Definition

The aggregate amount of foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6479006&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 235

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-05(a))

-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537907-122884

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Subparagraph a

-Article 9

+ Details

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- Definition

The aggregate amount of domestic or foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) that total to less than $100,000.

+ References

No definition available.

+ Details

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