REGULATORY MATTERS, COMMITMENTS AND CONTINGENCIES - Regulatory capital positions (Detail) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
First BanCorp [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,433,953	$ 2,416,682
Total Capital (to Risk-Weighted Assets) Actual Ratio	0.2050	0.2037
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 949,637	$ 948,890
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.080	0.080
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,112,630	$ 2,053,045
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	17.80%	17.31%
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required For Captial Adequacy	$ 534,171	$ 533,751
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required For Captial Adequacy Ratio	4.50%	4.50%
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,112,630	$ 2,089,149
Tier 1 Captial (to Risk-Weighted Assets) Actual Ratio	0.1780	0.1761
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 712,228	$ 711,667
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.060	0.060
Leverage Ratio Actual Amount	$ 2,112,630	$ 2,089,149
Leverage Ratio Actual Ratio	0.1014	0.1126
Leverage Ratio Required For Captial Adequacy	$ 833,091	$ 742,352
Leverage Ratio Required For Capital Adequancy Ratio	0.040	0.040
FirstBank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,401,390	$ 2,360,493
Total Capital (to Risk-Weighted Assets) Actual Ratio	0.2023	0.1991
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 949,556	$ 948,624
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.080	0.080
Total Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 1,186,944	$ 1,185,780
Total Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	0.100	0.100
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,150,317	$ 1,903,251
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	18.12%	16.05%
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required For Captial Adequacy	$ 534,125	$ 533,601
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required For Captial Adequacy Ratio	4.50%	4.50%
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 771,514	$ 770,757
Common Equity Tier 1 Captial (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	6.50%	6.50%
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,258,317	$ 2,211,251
Tier 1 Captial (to Risk-Weighted Assets) Actual Ratio	0.1903	0.1865
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 712,167	$ 711,468
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.060	0.060
Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 949,556	$ 948,624
Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	0.080	0.080
Leverage Ratio Actual Amount	$ 2,258,317	$ 2,211,251
Leverage Ratio Actual Ratio	0.1085	0.1192
Leverage Ratio Required For Captial Adequacy	$ 832,773	$ 741,841
Leverage Ratio Required For Capital Adequancy Ratio	0.040	0.040
Leverage Ratio Required To Be Well Capitalized	$ 1,040,967	$ 927,301
Leverage Ratio Required To Be Well Capitalized Ratio	0.050	0.050

Common Equity Tier 1 capital divided by risk weighted assets as defined by new Basel III rule.

No definition available.

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatio
Namespace Prefix:	fbp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatioCapitalAdequacy
Namespace Prefix:	fbp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Minimun common equity tier 1 capital to risk weight assets ratio for well capitalized purposes plus capital conservation buffer as required by Basel III rule.

+ References

No definition available.

+ Details

Name:	fbp_CommonEquityTier1CapitalToRiskWeightAssetsRatioWellCapitalized
Namespace Prefix:	fbp_
Data Type:	dtr-types:percentItemType
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
-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

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

No definition available.

+ 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: