REGULATORY MATTERS, COMMITMENTS AND CONTINGENCIES - Regulatory Capital Positions (Details) $ in Thousands	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
First BanCorp [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,366,470	$ 2,404,581
Total Capital (to Risk-Weighted Assets) Actual Ratio	0.1796	0.1802
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 1,054,347	$ 1,067,380
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	$ 2,190,351	$ 2,177,748
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	0.1662	0.1632
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 593,070	$ 600,401
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.045	0.045
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,190,351	$ 2,177,748
Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	0.1662	0.1632
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 790,760	$ 800,535
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.060	0.060
Leverage Ratio Actual Amount	$ 2,190,351	$ 2,177,748
Leverage Ratio Actual Ratio	0.1120	0.1107
Leverage Ratio Required For Capital Adequacy	$ 782,277	$ 786,937
Leverage Ratio Required For Capital Adequacy Ratio	0.040	0.040
FirstBank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets) Actual	$ 2,315,631	$ 2,369,441
Total Capital (to Risk-Weighted Assets) Actual Ratio	0.1758	0.1776
Total Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 1,054,043	$ 1,067,033
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	$ 1,317,554	$ 1,333,791
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	$ 2,050,369	$ 2,102,512
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	0.1556	0.1576
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 592,899	$ 600,206
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy Ratio	0.045	0.045
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized	$ 856,410	$ 866,964
Common Equity Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	0.065	0.065
Tier 1 Capital (to Risk-Weighted Assets) Actual	$ 2,150,369	$ 2,202,512
Tier 1 Capital (to Risk-Weighted Assets) Actual Ratio	0.1632	0.1651
Tier 1 Capital (to Risk-Weighted Assets) Required For Capital Adequacy	$ 790,532	$ 800,275
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	$ 1,054,043	$ 1,067,033
Tier 1 Capital (to Risk-Weighted Assets) Required To Be Well Capitalized Ratio	0.080	0.080
Leverage Ratio Actual Amount	$ 2,150,369	$ 2,202,512
Leverage Ratio Actual Ratio	0.1100	0.1120
Leverage Ratio Required For Capital Adequacy	$ 782,027	$ 786,712
Leverage Ratio Required For Capital Adequacy Ratio	0.040	0.040
Leverage Ratio Required To Be Well Capitalized	$ 977,533	$ 983,390
Leverage Ratio Required To Be Well Capitalized Ratio	0.050	0.050

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

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

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

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Amount of total capital as defined by regulatory framework.

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

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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/1943274/2147477270/942-505-50-1

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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/1943274/2147477270/942-505-50-1B

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