NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 10) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Performing loan
Restructured loans disclosures
Allowance for troubled debt restructurings loans receivable	$ 9,200	$ 10,500
Nonperforming loan
Restructured loans disclosures
Allowance for troubled debt restructurings loans receivable	$ 61	$ 139

The reserve to cover probable credit losses related to financing receivables that have been modified by troubled debt restructurings.

No definition available.

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