| Document and Entity Information | Sep. 01, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Amendment Description | Amendment No. 1 |
| Document Period End Date | Sep. 1, 2020 |
| Entity Registrant Name | First BanCorp. |
| Entity Incorporation, State or Country Code | PR |
| Entity File Number | 001-14793 |
| Entity Tax Identification Number | 66-0561882 |
| Entity Address, Address Line One | 1519 Ponce de Leon Ave. |
| Entity Address, Address Line Two | P.O. Box 9146 |
| Entity Address, City or Town | San Juan |
| Entity Address, Country | PR |
| Entity Address, Postal Zip Code | 00908-0146 |
| City Area Code | 787 |
| Local Phone Number | 729-8200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001057706 |
| Title of 12(b) Security | Common Stock ($0.10 par value) |
| Trading Symbol | FBP |
| Security Exchange Name | NYSE |
