Alternative Investments, Unfunded Investment Commitments

No definition available.

Name:	banc_AlternativeInvestmentsUnfundedInvestmentCommitments
Namespace Prefix:	banc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Other Commitments, Origination of Loans, Period

+ References

No definition available.

+ Details

Name:	banc_OtherCommitmentsOriginationofLoansPeriod
Namespace Prefix:	banc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Related Party Transaction, Maximum Commitment

+ References

No definition available.

+ Details

Name:	banc_RelatedPartyTransactionMaximumCommitment
Namespace Prefix:	banc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Related Party Transaction, Term Of Contract

+ References

No definition available.

+ Details

Name:	banc_RelatedPartyTransactionTermOfContract
Namespace Prefix:	banc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the carrying amount of loans and leases for which agreements to acquire or dispose exist.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61044-112788

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61082-112788

+ Details

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

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

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=banc_JumboMortgageLoanSaleCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banc_ToBeAnnouncedCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=banc_BestEffortsCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=banc_LosAngelesFootballClubLAFCNamingRightsRevenueRightsAndOtherSponsorshipRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOAN COMMITMENTS AND OTHER RELATED ACTIVITIES - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	Aug. 22, 2016	Apr. 06, 2015	Mar. 31, 2017
Other Commitments [Line Items]
Commitments to make loans, period, maximum			30 days
Commitments to sell loans under residential mortgage division			$ 663,600
Expenses from transactions with related parties		$ 263
Alternative investments unfunded investment commitments			111,700
Affordable Housing Fund Investment
Other Commitments [Line Items]
Alternative investments unfunded investment commitments			335
Small Business Investment Companies
Other Commitments [Line Items]
Alternative investments unfunded investment commitments			12,200
Other Investments
Other Commitments [Line Items]
Alternative investments unfunded investment commitments			111,800
Jumbo SFR mortgage loan sale commitments
Other Commitments [Line Items]
Commitments to sell loans under residential mortgage division			355,000
TBAs commitments
Other Commitments [Line Items]
Commitments to sell loans under residential mortgage division			641,000
Best efforts commitments
Other Commitments [Line Items]
Commitments to sell loans under residential mortgage division			22,600
Interest rate lock commitments
Other Commitments [Line Items]
Commitments to sell loans under residential mortgage division			312,500
Los Angeles Football Club (LAFC) Naming Rights, Revenue Rights, And Other Sponsorship Rights
Other Commitments [Line Items]
Maximum commitment			$ 100,000
Related party term of contract	15 years		15 years
Payments for naming rights			$ 10,000