Investment Securities - Contractual Maturities of Securities Available-for-Sale (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	$ 12,573
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	569,156
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	2,121,082
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	4,067,130
Total	6,769,941
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	12,519
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	532,664
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	1,858,125
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(3,488,020)
Total	5,891,328
Agency residential MBS
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	2,760,670
Total	2,760,670
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(2,291,234)
Total	2,291,234
Agency commercial MBS
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	500,086
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	358,770
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	28,925
Total	887,781
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	469,960
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	310,816
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(27,144)
Total	807,920
Agency residential CMOs
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	201,260
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	603,301
Total	804,561
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	178,062
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(558,420)
Total	736,482
Municipal securities
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	7,557
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	44,019
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	338,647
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	89,908
Total	480,131
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	7,536
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	38,940
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	284,872
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(83,851)
Total	415,199
U.S. Treasury securities
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	4,997
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	766,085
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	0
Total	771,082
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	4,965
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	658,424
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	0
Total	663,389
Corporate debt securities
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	20,500
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	353,946
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	0
Total	374,446
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	19,475
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	326,067
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	0
Total	345,542
Collateralized loan obligations
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	101,156
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	264,188
Total	365,344
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	98,676
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(255,086)
Total	353,762
Private label residential CMOs
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	241,779
Total	241,779
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(197,955)
Total	197,955
Asset-backed securities
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	1,218
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	31,302
Total	32,520
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	1,208
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(30,814)
Total	32,022
Private label commercial MBS
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	31,634
Total	31,634
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(29,178)
Total	29,178
SBA securities
Schedule of Investments [Line Items]
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due Within One Year	19
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After One Year Through Five Years	4,551
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Amortized Cost, Due After Ten Years	15,423
Total	19,993
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year	18
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due Within One Year Through Five Years	4,289
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Five Years Through Ten Years	0
Contractual Maturities of Securities Available-for-Sale, Fair Value, Due After Ten Years	(14,338)
Total	$ 18,645

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803

+ Details

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

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123599081&loc=d3e62586-112803

+ Details

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

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

+ Details

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

- Definition

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_ScheduleOfInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=pacw_GovernmentagencyandgovernmentsponsoredenterprisecollateralizedmortgageobligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CollateralizedLoanObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=pacw_PrivateLabelCollateralizedMortgageObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=pacw_SBAassetbackedsecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: