OTHER REAL ESTATE OWNED - Expenses Related to Foreclosed Assets Included in Loan Servicing and Foreclosure Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Real Estate Owned, Disclosure of Detailed Components [Abstract]
Net loss on sales	$ (16)	$ (130)	$ (13)	$ (99)
Operating expenses, net of rental income	(32)	(11)	(134)	(24)
Total	$ (48)	$ (141)	$ (147)	$ (123)

Operating expenses, net of rental income, relating to other real estate and foreclosed assets.

No definition available.

Name:	banc_ForeclosedRealEstateExpenseNetofRentalIncome
Namespace Prefix:	banc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.14(d))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The net cost of operation of other real estate (including provisions for real estate losses, rental income, and gains and losses on sales of real estate).

+ References

+ Details

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

- References

No definition available.

+ Details

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