Loans and Leases - Components of Leases Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Direct Financing Lease, Net Investment in Leases [Abstract]
Lease payments receivable	$ 124,550	$ 147,729
Unguaranteed residual assets	18,404	20,806
Deferred costs and other	550	655
Aggregate net investment in leases	$ 143,504	$ 169,190

Direct Financing Lease, Deferred Selling Profit And Other

No definition available.

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

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981

+ Details

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

- Definition

Amount of net investment in direct financing lease.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor.

+ References

+ Details

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