Nature of Operations and Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
Dec. 31, 2021 USD ($) bank_branch reportable_segment
Business Acquisition [Line Items]
Threshold for loans that are considered individually significant for allowance analysis purposes \| $	$ 250,000
Share-based Compensation Arrangement by Share-based Payment Award, Performance Period	3 years
Derivative Instruments and Hedges, Liabilities \| $	$ 0
Number of Reportable Segments \| reportable_segment	1
Minimum
Business Acquisition [Line Items]
Share-Based Compensation Arrangement By Share-based Payment Award, Performance Target, Maxium	150.00%
Maximum
Business Acquisition [Line Items]
Share-Based Compensation Arrangement By Share-based Payment Award, Performance Target, Maxium	200.00%
Core Deposits [Member] \| Minimum
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Core Deposits [Member] \| Maximum
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Customer Relationships [Member] \| Minimum
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	4 years
Customer Relationships [Member] \| Maximum
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Furniture and Fixtures [Member] \| Minimum
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] \| Maximum
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Building [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life	30 years
Limited Partnership \| Minimum
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	5.00%
Equity Securities \| Minimum
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	20.00%
Equity Securities \| Maximum
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
CALIFORNIA
Business Acquisition [Line Items]
Retail Branch Locations	69
NORTH CAROLINA
Business Acquisition [Line Items]
Retail Branch Locations	1
COLORADO
Business Acquisition [Line Items]
Retail Branch Locations	1

Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners

No definition available.

Name:	pacw_NoncontrollingInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	pacw_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Retail Branch Locations

+ References

No definition available.

+ Details

Name:	pacw_RetailBranchLocations
Namespace Prefix:	pacw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-Based Compensation Arrangement By Share-based Payment Award, Performance Target

+ References

No definition available.

+ Details

Name:	pacw_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceTarget
Namespace Prefix:	pacw_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Performance Period

+ References

No definition available.

+ Details

Name:	pacw_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriod
Namespace Prefix:	pacw_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Threshold for loans that are considered individually significant for allowance analysis purposes

+ References

No definition available.

+ Details

Name:	pacw_Thresholdforloansthatareconsideredindividuallysignificantforallowanceanalysispurposes
Namespace Prefix:	pacw_
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_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum as of the balance sheet date of the (a) fair values of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and (b) the carrying amounts of the liabilities arising from financial instruments or contracts used to mitigate a specified risk (hedge), and which are expected to be extinguished or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CoreDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	dei_EntityByLocationAxis=stpr_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_EntityByLocationAxis=stpr_NC
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_EntityByLocationAxis=stpr_CO
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: