CUSTOMER DEPOSIT ACCOUNTS (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Time deposits:
Time deposits within the Certificate of Deposit Account Registry Service (CDARS) program	$ 180.0	$ 203.3

Represents the time deposits within the Certificate of Deposit Account Registry Service (CDARS) program that allows customers with deposits in excess of FDIC-insured limits to obtain full coverage on time deposits through a network of banks within the CDARS program.

No definition available.

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