REGULATORY CAPITAL MATTERS - Actual and Required Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Banc of California, NA
Total risk-based capital
Total risk-based capital ratio, actual amount	$ 1,011,587	$ 1,007,762
Total risk-based capital ratio, actual ratio (percent)	0.1727	0.1746
Total risk-based capital ratio, minimum capital requirements amount	$ 468,698	$ 461,843
Total risk-based capital ratio, minimum capital requirements ratio (percent)	0.0800	0.0800
Total risk-based capital ratio, minimum required to be well capitalized under prompt corrective action provisions amount	$ 585,873	$ 577,304
Total risk-based capital ratio, minimum required to be well capitalized under prompt corrective action provisions ratio (percent)	0.1000	0.1000
Tier 1 risk-based capital
Tier 1 risk-based capital ratio, actual amount	$ 938,346	$ 946,049
Tier 1 risk-based capital ratio, actual ratio (percent)	0.1602	0.1639
Tier 1 risk-based capital ratio, minimum capital requirements amount	$ 351,524	$ 346,382
Tier 1 risk-based capital ratio, minimum capital requirements ratio (percent)	0.0600	0.0600
Tier 1 risk-based capital ratio, minimum required to be well capitalized under prompt corrective action provisions amount	$ 468,698	$ 461,843
Tier 1 risk-based capital ratio, minimum required to be well capitalized under prompt corrective action provisions ratio (percent)	0.0800	0.0800
Common equity tier 1 capital
Common equity tier 1 capital ratio, actual amount	$ 938,346	$ 946,049
Common equity tier 1 capital ratio, actual ratio (percent)	0.1602	0.1639
Common equity tier 1 capital ratio, minimum capital requirements amount	$ 263,643	$ 259,787
Common equity tier 1 capital ratio, minimum capital requirements ratio (percent)	4.50%	4.50%
Common equity tier 1 capital ratio, minimum required to be well capitalized under prompt corrective action provisions amount	$ 380,817	$ 375,247
Common equity tier 1 capital ratio, minimum required to be well capitalized under prompt corrective action provisions ratio (percent)	6.50%	6.50%
Tier 1 leverage
Tier 1 leverage ratio, actual amount	$ 938,346	$ 946,049
Tier 1 leverage ratio, actual ratio (percent)	0.1219	0.1202
Tier 1 leverage ratio, minimum capital requirements amount	$ 307,894	$ 314,707
Tier 1 leverage ratio, minimum capital requirements ratio (percent)	0.0400	0.0400
Tier 1 leverage ratio, minimum required to be well capitalized under prompt corrective action provisions amount	$ 384,868	$ 393,383
Tier 1 leverage ratio, minimum required to be well capitalized under prompt corrective action provisions ratio (percent)	0.0500	0.0500
Banc of California, Inc.
Total risk-based capital
Total risk-based capital ratio, actual amount	$ 996,466	$ 921,892
Total risk-based capital ratio, actual ratio (percent)	0.1701	0.1590
Total risk-based capital ratio, minimum capital requirements amount	$ 468,628	$ 463,950
Total risk-based capital ratio, minimum capital requirements ratio (percent)	0.0800	0.0800
Tier 1 risk-based capital
Tier 1 risk-based capital ratio, actual amount	$ 840,501	$ 860,179
Tier 1 risk-based capital ratio, actual ratio (percent)	0.1435	0.1483
Tier 1 risk-based capital ratio, minimum capital requirements amount	$ 351,471	$ 347,963
Tier 1 risk-based capital ratio, minimum capital requirements ratio (percent)	0.0600	0.0600
Common equity tier 1 capital
Common equity tier 1 capital ratio, actual amount	$ 655,623	$ 670,355
Common equity tier 1 capital ratio, actual ratio (percent)	0.1119	0.1156
Common equity tier 1 capital ratio, minimum capital requirements amount	$ 263,603	$ 260,972
Common equity tier 1 capital ratio, minimum capital requirements ratio (percent)	4.50%	4.50%
Tier 1 leverage
Tier 1 leverage ratio, actual amount	$ 840,501	$ 860,179
Tier 1 leverage ratio, actual ratio (percent)	0.1090	0.1089
Tier 1 leverage ratio, minimum capital requirements amount	$ 308,555	$ 315,825
Tier 1 leverage ratio, minimum capital requirements ratio (percent)	0.0400	0.0400

Common Capital [Abstract]

No definition available.

Name:	banc_CommonCapitalAbstract
Namespace Prefix:	banc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Tier One Risk Based Common Capital Required for Capital Adequacy to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	banc_TierOneRiskBasedCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets
Namespace Prefix:	banc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier One Risk Based Common Capital Required to be Well Capitalized to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	banc_TierOneRiskBasedCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix:	banc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826

+ Details

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

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum total risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Common Equity Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

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

- Definition

Ratio of Common Equity Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CommonEquityTierOneCapitalRatio
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Common Equity Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

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

- Definition

Amount of minimum Common Equity Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of minimum Tier 1 leverage capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

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

- Definition

Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 capital to average assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of minimum Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

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

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

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

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=banc_BancOfCaliforniaNationalAssociationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: