Alternative Investments, Liquidation Period

No definition available.

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

- Definition

Alternative Investments, Unfunded Investment Commitments

+ References

No definition available.

+ Details

Name:	banc_AlternativeInvestmentsUnfundedInvestmentCommitments
Namespace Prefix:	banc_
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_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

+ Details

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

- Definition

This is the principal amount outstanding for loans which are in the process of being securitized as of the date of the statement of financial position (across all types of loans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=64830801&loc=d3e107314-111719

+ Details

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

- Definition

Amount of expense recognized in the income statement for a decrease in valuation of real estate owned (REO).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(4))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_RealEstateOwnedValuationAllowanceProvision1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of contractually collectible principal associated with a financial asset expected not to be collected due to default by the borrower.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746

+ Details

Name:	us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueExpectedCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_FairValueByAssetClassAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

FAIR VALUES OF FINANCIAL INSTRUMENTS - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation allowance for other real estate owned	$ 16	$ 16	$ 25	$ 38
Alternative investments liquidation period			10 years
Alternative investments unfunded investment commitments	58,400		$ 58,400
Net gains (losses) attributable to instrument-specific credit risk	0	$ 0	0	$ 0
Affordable Housing Fund Investment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments unfunded investment commitments	10,300		10,300
Small Business Investment Companies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments unfunded investment commitments	12,900		12,900
Other Investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative investments unfunded investment commitments	60,400		60,400
Agency mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregated unpaid principal balance	$ 47,700		$ 47,700		$ 18,600
Expected loss rate			1.58%		1.85%