Loans and Leases (Details 1) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Delinquent loans in loan portfolio
30-89 Days Past Due	$ 12,232	$ 9,788
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	36,523	11,085
Financing Receivable, Past Due	48,755	20,873
Current	19,034,622	18,825,999
Loans held for investment, net	19,083,377	18,846,872
Mortgages [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	7,350	4,553
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	29,518	6,721
Financing Receivable, Past Due	36,868	11,274
Current	7,863,068	7,961,473
Loans held for investment, net	7,899,936	7,972,747
Real Estate Construction [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	759	1,429
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	0
Financing Receivable, Past Due	759	1,429
Current	3,359,522	2,736,373
Loans held for investment, net	3,360,281	2,737,802
Commercial Portfolio Segment [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	2,863	2,800
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	6,894	4,164
Financing Receivable, Past Due	9,757	6,964
Current	7,493,148	7,688,532
Loans held for investment, net	7,502,905	7,695,496
Consumer Portfolio Segment [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	1,260	1,006
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	111	200
Financing Receivable, Past Due	1,371	1,206
Current	318,884	439,621
Loans held for investment, net	320,255	440,827
Asset Based [Member] \| Commercial Portfolio Segment [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	0	19
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,128	0
Financing Receivable, Past Due	2,128	19
Current	3,427,155	3,748,388
Loans held for investment, net	3,429,283	3,748,407
Venture Capital Loans [Member] \| Commercial Portfolio Segment [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	540	0
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	0
Financing Receivable, Past Due	540	0
Current	1,697,968	2,179,422
Loans held for investment, net	1,698,508	2,179,422
Other Commercial [Member] \| Commercial Portfolio Segment [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	2,323	2,781
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	4,766	4,164
Financing Receivable, Past Due	7,089	6,945
Current	2,368,025	1,760,722
Loans held for investment, net	2,375,114	1,767,667
Commercial Real Estate Construction Loan Receivable [Member] \| Real Estate Construction [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	0	0
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	0
Financing Receivable, Past Due	0	0
Current	1,117,121	1,082,368
Loans held for investment, net	1,117,121	1,082,368
Residential Real Estate Construction Financing Receivable [Member] \| Real Estate Construction [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	759	1,429
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	0
Financing Receivable, Past Due	759	1,429
Current	2,242,401	1,654,005
Loans held for investment, net	2,243,160	1,655,434
Commercial Real Estate [Member] \| Mortgages [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	6,750	2,448
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	29,145	5,919
Financing Receivable, Past Due	35,895	8,367
Current	4,060,776	4,194,320
Loans held for investment, net	4,096,671	4,202,687
Residential Real Estate [Member] \| Mortgages [Member]
Delinquent loans in loan portfolio
30-89 Days Past Due	600	2,105
Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	373	802
Financing Receivable, Past Due	973	2,907
Current	3,802,292	3,767,153
Loans held for investment, net	$ 3,803,265	$ 3,770,060

Financing Receivable Recorded Investment, Current No Past Due

No definition available.

Name:	pacw_FinancingReceivableRecordedInvestmentCurrentNoPastDue
Namespace Prefix:	pacw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivable recorded investment 30 to 89 days past due.

+ References

No definition available.

+ Details

Name:	pacw_FinancingReceivableRecordedInvestmentThirtyToEightyNineDaysPastDue
Namespace Prefix:	pacw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Loan Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due - replaces Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due

+ References

No definition available.

+ Details

Name:	pacw_LoanReceivableRecordedInvestmentEqualtoGreaterthan90DaysPastDue
Namespace Prefix:	pacw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Receivables, Past Due [Abstract]

+ References

No definition available.

+ Details

Name:	pacw_ReceivablesPastDueAbstract
Namespace Prefix:	pacw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of financing receivable past due.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524

+ Details

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

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=pacw_RealEstateConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pacw_CommercialCollateralizedFinancingReceivableLoanTypeAxis=pacw_AssetBasedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pacw_CommercialCollateralizedFinancingReceivableLoanTypeAxis=pacw_VentureCapitalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pacw_CommercialCollateralizedFinancingReceivableLoanTypeAxis=pacw_OtherCommercialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pacw_RealEstateConstructionLoanTypeAxis=pacw_CommercialRealEstateConstructionLoanReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pacw_RealEstateConstructionLoanTypeAxis=pacw_ResidentialRealEstateConstructionFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: