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Loans Receivable and Allowance for Credit Losses (Summary of Activities in Allowance for loan losses by Portfolio Segments and Unfunded Credit Commitments) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Allowance for unfunded credit reserves |  |
Allowance for unfunded credit commitments, beginning of period | $ 33,500 |
Provision for credit losses | 0 | $ 73,870
Allowance for unfunded credit commitments, end of period | 32,400 |
Unfunded Credit Commitments |  |
Allowance for unfunded credit reserves |  |
Allowance for unfunded credit commitments, beginning of period | 33,577 | 11,158
Provision for credit losses | (1,048) | (786)
Allowance for unfunded credit commitments, end of period | 32,529 | 20,829
Cumulative Effect, Period Of Adoption, Adjustment |  |
Allowance for unfunded credit reserves |  |
Allowance for unfunded credit commitments, beginning of period | $ 0 | $ 10,457

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- Definition Reflects the Allowance for Unfunded Credit Commitments + References No definition available. + Details
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Namespace Prefix: | ewbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
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- Details
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- Details
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