LOAN PORTFOLIO - Loan Modifications are Considered TDRs (Detail) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016 USD ($) numberofcontracts	Dec. 31, 2015 USD ($) numberofcontracts
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	688	622
Pre-Modification Outstanding Recorded Investment	$ 16,754	$ 31,858
Post-Modification Outstanding Recorded Investment	$ 16,219	$ 31,601
Non Fha Va Residential Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	58	81
Pre-Modification Outstanding Recorded Investment	$ 9,012	$ 11,495
Post-Modification Outstanding Recorded Investment	$ 8,459	$ 11,265
Commercial Mortgage Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	0	8
Pre-Modification Outstanding Recorded Investment	$ 0	$ 12,821
Post-Modification Outstanding Recorded Investment	$ 0	$ 12,931
Commercial And Industrial Loan [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 1,681
Post-Modification Outstanding Recorded Investment	$ 0	$ 1,681
Consumer Auto Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	258	146
Pre-Modification Outstanding Recorded Investment	$ 4,981	$ 2,173
Post-Modification Outstanding Recorded Investment	$ 4,981	$ 2,130
Finance Leases [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	36	8
Pre-Modification Outstanding Recorded Investment	$ 940	$ 233
Post-Modification Outstanding Recorded Investment	$ 940	$ 184
Other Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	336	377
Pre-Modification Outstanding Recorded Investment	$ 1,821	$ 3,391
Post-Modification Outstanding Recorded Investment	$ 1,839	$ 3,346
Commercial Construction [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	0
Pre-Modification Outstanding Recorded Investment	$ 0
Post-Modification Outstanding Recorded Investment	$ 0
Residential Construction [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	0
Pre-Modification Outstanding Recorded Investment	$ 0
Post-Modification Outstanding Recorded Investment	$ 0
Land Construction [Member]
Financing Receivable Modifications [Line Items]
Number of Contracts \| numberofcontracts	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 64
Post-Modification Outstanding Recorded Investment	$ 0	$ 64

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.

No definition available.

+ Details

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

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fbp_CommercialAndIndustrialLoanMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_FinanceLeasesPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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