Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (97,967,000)	[1]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	14,668,000	[2]
Unfunded Loan Commitment [Member]
Allowance for Unfunded Credit Commitments	ewbc_AllowanceforUnfundedCreditCommitments	$ 21,615,000

[1] Represents the impact of the adoption of ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) in the first quarter of 2020. Refer to Note 2 — Summary of Significant Accounting Policies to the Consolidated Financial Statements in this Quarterly Report on Form 10-Q (“this Form 10-Q”) for additional information.

[2] Represents the impact of the adoption of Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) and subsequent related ASUs in the first quarter of 2019.