INVESTMENTS IN QUALIFIED AFFORDABLE HOUSING PARTNERSHIPS, TAX CREDIT AND OTHER INVESTMENTS, NET (Details 2) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
INVESTMENTS IN QUALIFIED AFFORDABLE HOUSING PARTNERSHIPS, TAX CREDIT AND OTHER INVESTMENTS, NET
Investments in tax credit and other investments	$ 170,400		$ 187,200
Total unfunded commitments for investments in tax credit and other investments	105,700		$ 113,200
Noninterest expense — amortization of tax credit and other investments	$ 14,155	$ 6,299

Amount of commitment or contingent commitments to investments in certain limited partnerships that qualify for Community Reinvestment Act (CRA) credits or other types of tax credits.

No definition available.

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