Name:	pacw_AllowanceforCreditLossesChangeinMethodofCalculatingProbableCreditLoss
Namespace Prefix:	pacw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

number of branches

No definition available.

Name:	pacw_Numberofbranches
Namespace Prefix:	pacw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Retail Branch Locations

No definition available.

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

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.

No definition available.

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

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of assets acquired at the acquisition date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

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

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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

The number of businesses acquired by the entity during the period.

No definition available.

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

Name:	us-gaap_ConcentrationRiskByTypeAxis=pacw_PurchasedCreditImpairedLoansandLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=pacw_Pre2018ALLLMethodology2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	pacw_ALLLCreditLossSegmentsAxis=pacw_Thirtyfour34Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=pacw_NewALLLMethodology2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	pacw_ALLLCreditLossSegmentsAxis=pacw_Twentyone21Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=pacw_AccountingStandardsUpdate201802Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	invest_InvestmentAxis=pacw_LimitedPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_BusinessAcquisitionAxis=pacw_ElDoradoSavingsBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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

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