Financing Receivable, Collateral Dependent

No definition available.

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Namespace Prefix:	ewbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ 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)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(2))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableImpairedLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ewbc_CommercialAndIndustrialLoanMember
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- Details

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- Details

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- Details

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- Details

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Loans Receivable and Allowance for Credit Losses (Impaired Loans) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Impaired loans disclosures
Allowance for loan losses			$ 618,252		$ 358,287
Commercial lending
Impaired loans disclosures
Collateral dependent loan			109,700
Commercial lending \| Commercial and industrial (“C&I”)
Impaired loans disclosures
Allowance for loan losses	$ 218,869	$ 218,869	389,021	$ 380,723	238,376	$ 205,503	$ 189,117
Commercial lending \| Commercial real estate (“CRE”)
Impaired loans disclosures
Allowance for loan losses	37,473	37,473	166,810	176,040	40,509	39,811	40,666
Commercial lending \| Real estate loan \| Multifamily residential
Impaired loans disclosures
Allowance for loan losses	20,307	20,307	23,807	25,058	22,826	19,280	19,885
Commercial lending \| Construction and land
Impaired loans disclosures
Allowance for loan losses	29,171	29,171	10,401	18,551	19,404	22,961	20,290
Consumer lending
Impaired loans disclosures
Collateral dependent loan			17,600
Consumer lending \| Real estate loan \| Single-family residential
Impaired loans disclosures
Allowance for loan losses	29,935	29,935	22,622	25,314	28,527	32,763	31,340
Consumer lending \| HELOCs
Impaired loans disclosures
Allowance for loan losses	5,856	5,856	3,273	3,867	5,265	6,177	5,774
Consumer lending \| Other consumer
Impaired loans disclosures
Allowance for loan losses	3,965	3,965	$ 2,318	$ 2,518	3,380	$ 4,130	$ 4,250
Non-PCI Loans
Impaired loans disclosures
Unpaid Principal Balance					266,772
Recorded Investment With No Allowance					129,748
Recorded Investment With Allowance					68,369
Total Recorded Investment					198,117
Related Allowance					5,593
Average Recorded Investment	225,800	287,022
Recognized Interest Income	673	3,173
Allowance for loan losses					358,287
Non-PCI Loans \| Commercial lending
Impaired loans disclosures
Unpaid Principal Balance					226,918
Recorded Investment With No Allowance					115,116
Recorded Investment With Allowance					44,699
Total Recorded Investment					159,815
Related Allowance					3,033
Average Recorded Investment	184,135	237,209
Recognized Interest Income	512	2,698
Non-PCI Loans \| Commercial lending \| Commercial and industrial (“C&I”)
Impaired loans disclosures
Unpaid Principal Balance					174,656
Recorded Investment With No Allowance					73,956
Recorded Investment With Allowance					40,086
Total Recorded Investment					114,042
Related Allowance					2,881
Average Recorded Investment	150,063	198,024
Recognized Interest Income	340	2,156
Non-PCI Loans \| Commercial lending \| Commercial real estate (“CRE”)
Impaired loans disclosures
Unpaid Principal Balance					27,601
Recorded Investment With No Allowance					20,098
Recorded Investment With Allowance					1,520
Total Recorded Investment					21,618
Related Allowance					97
Average Recorded Investment	28,846	33,329
Recognized Interest Income	114	363
Non-PCI Loans \| Commercial lending \| Real estate loan \| Multifamily residential
Impaired loans disclosures
Unpaid Principal Balance					4,965
Recorded Investment With No Allowance					1,371
Recorded Investment With Allowance					3,093
Total Recorded Investment					4,464
Related Allowance					55
Average Recorded Investment	5,226	5,856
Recognized Interest Income	58	179
Non-PCI Loans \| Commercial lending \| Construction and land
Impaired loans disclosures
Unpaid Principal Balance					19,696
Recorded Investment With No Allowance					19,691
Recorded Investment With Allowance					0
Total Recorded Investment					19,691
Related Allowance					0
Non-PCI Loans \| Commercial lending \| Total CRE
Impaired loans disclosures
Unpaid Principal Balance					52,262
Recorded Investment With No Allowance					41,160
Recorded Investment With Allowance					4,613
Total Recorded Investment					45,773
Related Allowance					152
Average Recorded Investment	34,072	39,185
Recognized Interest Income	172	542
Non-PCI Loans \| Consumer lending
Impaired loans disclosures
Unpaid Principal Balance					39,854
Recorded Investment With No Allowance					14,632
Recorded Investment With Allowance					23,670
Total Recorded Investment					38,302
Related Allowance					2,560
Average Recorded Investment	41,665	49,813
Recognized Interest Income	161	475
Non-PCI Loans \| Consumer lending \| Real estate loan \| Single-family residential
Impaired loans disclosures
Unpaid Principal Balance					23,626
Recorded Investment With No Allowance					8,507
Recorded Investment With Allowance					13,704
Total Recorded Investment					22,211
Related Allowance					35
Average Recorded Investment	23,779	27,758
Recognized Interest Income	124	382
Non-PCI Loans \| Consumer lending \| HELOCs
Impaired loans disclosures
Unpaid Principal Balance					13,711
Recorded Investment With No Allowance					6,125
Recorded Investment With Allowance					7,449
Total Recorded Investment					13,574
Related Allowance					8
Average Recorded Investment	15,382	19,529
Recognized Interest Income	37	93
Non-PCI Loans \| Consumer lending \| Total residential mortgage
Impaired loans disclosures
Unpaid Principal Balance					37,337
Recorded Investment With No Allowance					14,632
Recorded Investment With Allowance					21,153
Total Recorded Investment					35,785
Related Allowance					43
Average Recorded Investment	39,161	47,287
Recognized Interest Income	161	475
Non-PCI Loans \| Consumer lending \| Other consumer
Impaired loans disclosures
Unpaid Principal Balance					2,517
Recorded Investment With No Allowance					0
Recorded Investment With Allowance					2,517
Total Recorded Investment					2,517
Related Allowance					$ 2,517
Average Recorded Investment	2,504	2,526
Recognized Interest Income	$ 0	$ 0