LOANS HELD FOR INVESTMENT - Financial Effects of the Permanent Modifications Granted to Borrowers Experiencing Financial Difficulty (Detail) - Permanent Modification [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2023
Residential Portfolio Segment [Member] \| Conventional Loan [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Term Extension (in months)	239 months	118 months
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Term Extension (in months)	72 months	72 months
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Construction Loans [Member] \| Commercial Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Automobile Loan [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Term Extension (in months)	27 months	25 months
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Personal Loans [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Term Extension (in months)	37 months	34 months
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Credit Card Receivables [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	16.26%	16.15%
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Other Loans [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Weighted-Average Term Extension (in months)	28 months	27 months
Weighted-Average Forgiveness of Principal and/or Interest	$ 0	$ 0
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Residential Portfolio Segment [Member] \| Conventional Loan [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	2.40%
Weighted-Average Term Extension (in months)		157 months
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.25%	0.25%
Weighted-Average Term Extension (in months)	64 months	64 months
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Construction Loans [Member] \| Commercial Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Automobile Loan [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	3.96%	3.64%
Weighted-Average Term Extension (in months)	30 months	30 months
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Personal Loans [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	5.41%	5.11%
Weighted-Average Term Extension (in months)	26 months	24 months
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Credit Card Receivables [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	0.00%	0.00%
Combination Of Interest Rate Below Market Reduction And Extended Maturity [Member] \| Other Loans [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable Modifications [Line Items]
Weighted-Average Interest Rate Reduction (%)	1.87%	1.92%
Weighted-Average Term Extension (in months)	22 months	24 months

Financing Receivable Excluding Accrued Interest Modification Increase Decrease From Modification

No definition available.

Name:	fbp_FinancingReceivableExcludingAccruedInterestModificationIncreaseDecreaseFromModification
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-42

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-42

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481933/310-10-55-12A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-33

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-34

+ Details

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

- Definition

Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481933/310-10-55-12A

+ Details

Name:	us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=us-gaap_ConventionalLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationNameAxis=fbp_PermanentModificationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_MortgageReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fbp_PersonalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CreditCardReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fbp_OtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=fbp_CombinationOfInterestRateBelowMarketReductionAndExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: