LOAN PORTFOLIO - Activity for Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Impaired Loans:
Balance at beginning of period	$ 945,407	$ 919,112
Loans determined impaired during the period	62,933	54,277
Charge-offs	(11,715)	(32,039)
Loans sold, net charge-offs	(1,137)fbp_ImpairedLoansSold	0fbp_ImpairedLoansSold
Increases to impaired loans (disbursements)	519	625
Foreclosures	(9,952)fbp_ForeclosuresOfImpairedLoans	(4,006)fbp_ForeclosuresOfImpairedLoans
Loans no longer considered impaired	(9,898)fbp_ImpairedLoansRemoved	(3,728)fbp_ImpairedLoansRemoved
Paid in full or partial payments	(21,176)	(54,853)
Balance at end of period	$ 954,981	$ 879,388

Amount of direct write-downs of financing receivables charged against the allowance related to impaired loans.

No definition available.

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

- Definition

Amount of real estate investments acquired through foreclosure during the period related to impaired loans.

+ References

No definition available.

+ Details

Name:	fbp_ForeclosuresOfImpairedLoans
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	fbp_ImpairedCommercialLoanStatisticAbstract
Namespace Prefix:	fbp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loans determined to be impaired during the period.

+ References

No definition available.

+ Details

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

- Definition

Disbursements during the period on existing commitments of Impaired loans.

+ References

No definition available.

+ Details

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

- Definition

Principal repayments related to Impaired Loans.

+ References

No definition available.

+ Details

Name:	fbp_ImpairedFinancingReceivablePaidOrPartialPayments
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of loans no longer reported as Impaired loans.

+ References

No definition available.

+ Details

Name:	fbp_ImpairedLoansRemoved
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Impaired loans sold during the quarter.

+ References

No definition available.

+ Details

Name:	fbp_ImpairedLoansSold
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant