REGULATORY MATTERS, COMMITMENTS, AND CONTINGENCIES - Regulatory capital positions (Detail) $ in Thousands	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
First BanCorp [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,396,564	$ 2,385,866
Total Capital (to Risk-Weighted Assets) Actual Ratio	19.15	19.21
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 1,001,189	$ 993,405
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	8.0	8.0
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,082,843	$ 2,052,333
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	16.64	16.53
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 563,169	$ 558,790
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	4.5	4.5
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,082,843	$ 2,052,333
Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	16.64	16.53
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 750,892	$ 745,054
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	6.0	6.0
Leverage Ratio Actual Amount	$ 2,082,843	$ 2,052,333
Leverage Ratio Actual Ratio	10.73	10.70
Leverage Ratio Required For Capital Adequacy	$ 776,742	$ 767,075
Leverage Ratio Required For Capital Adequacy Ratio	4.0	4.0
FirstBank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,326,581	$ 2,346,093
Total Capital (to Risk-Weighted Assets) Actual Ratio	18.59	18.90
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 1,001,046	$ 993,264
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	8.0	8.0
Total Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 1,251,307	$ 1,241,580
Total Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	10.0	10.0
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,069,732	$ 2,090,832
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	16.54	16.84
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 563,088	$ 558,711
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	4.5	4.5
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 813,350	$ 807,027
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	6.5	6.5
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,169,732	$ 2,190,832
Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	17.34	17.65
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 750,784	$ 744,948
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	6.0	6.0
Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 1,001,046	$ 993,264
Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	8.0	8.0
Leverage Ratio Actual Amount	$ 2,169,732	$ 2,190,832
Leverage Ratio Actual Ratio	11.18	11.43
Leverage Ratio Required For Capital Adequacy	$ 776,431	$ 766,714
Leverage Ratio Required For Capital Adequacy Ratio	4.0	4.0
Leverage Ratio Required To Be Well Capitalized	$ 970,539	$ 958,392
Leverage Ratio Required To Be Well Capitalized Ratio	5.0	5.0

Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio

No definition available.

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatio1
Namespace Prefix:	fbp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio

+ References

No definition available.

+ Details

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatioCapitalAdequacy1
Namespace Prefix:	fbp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio

+ References

No definition available.

+ Details

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatioWellCapitalized1
Namespace Prefix:	fbp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

+ Details

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

- 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
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B

+ 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

+ 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

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

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

+ Details

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

- 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

- 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

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

- Details

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