DEPOSITS - Narratives (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deposits [Line Items]
weighted average interest rate on total interest-bearing deposits	0.82%	0.93%
Overdrafts in demand deposits that were reclassified as loans	$ 800,000	$ 2,600,000
CDs in denominations of $100,000 or higher	4,300,000,000us-gaap_TimeDeposits100000OrMore	4,700,000,000us-gaap_TimeDeposits100000OrMore
Brokered certificates of deposit	2,887,046,000	3,142,023,000
Unamortized broker placement fees	6,100,000fbp_UnamortizedBrokerPlacementFees	9,100,000fbp_UnamortizedBrokerPlacementFees
Deposit accounts issued to government agencies with a carrying value	9,483,945,000us-gaap_Deposits	9,879,924,000us-gaap_Deposits
Amortization Of Broker Placement Fees	6,662,000fbp_AmortizationOfBrokerPlacementFees	7,900,000fbp_AmortizationOfBrokerPlacementFees	9,869,000fbp_AmortizationOfBrokerPlacementFees
Certificate Of Deposits Denominations	100,000fbp_CertificateOfDepositsDenominations
Public Funds Withdrawn Amount	341,600,000fbp_PublicFundsWithdrawnAmount
Amortized Cost [Member]
Deposits [Line Items]
Deposit Liabilities Collateral Issued Financial Instruments	634,000,000	784,000,000
Market Value [Member]
Deposits [Line Items]
Deposit Liabilities Collateral Issued Financial Instruments	624,800,000	761,900,000
Brokered Certificate of Deposits [Member]
Deposits [Line Items]
Weighted Average Interest Rate of Time Deposits, $100,000 or More	0.77%	0.97%
Government [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	400,700,000	705,800,000
Government [Member] \| Puerto Rico [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	227,400,000	546,500,000
Government [Member] \| Virgin Islands [Member]
Deposits [Line Items]
Deposit accounts issued to government agencies with a carrying value	$ 173,300,000	$ 159,300,000

Amortization of broker placement fees

No definition available.

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

- Definition

Denominations of certificate of deposits.

+ References

No definition available.

+ Details

Name:	fbp_CertificateOfDepositsDenominations
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Definition

The amount of public funds withdrawn by certain public corporations and agencies.

+ References

No definition available.

+ Details

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

- Definition

unamortized amount of costs for brokerage fees paid for issuance of brokered CDs.

+ References

No definition available.

+ Details

Name:	fbp_UnamortizedBrokerPlacementFees
Namespace Prefix:	fbp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of securities, mortgage loans, or other financial instruments pledged as collateral for deposits.

+ References

+ Details

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

- Definition

Amount of deposits held by the entity that have been reclassified as loan balances receivable, for example, but not limited to, overdrafts receivable.

+ References

+ Details

Name:	us-gaap_DepositLiabilitiesReclassifiedAsLoansReceivable1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

+ Details

Name:	us-gaap_Deposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic third-party deposits placed by or through the assistance of a deposit broker, also known as brokered deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositBrokered
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6479006&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 3

-Section V

-Paragraph A

-Subparagraph 4

+ Details

Name:	us-gaap_TimeDeposits100000OrMore
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The weighted average interest rate for all domestic deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_WeightedAverageRateDomesticDeposit
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	fbp_DeposistByTypeAxis=fbp_BrokeredCertificateOfDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fbp_DeposistByTypeAxis=us-gaap_GovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_EligibleItemOrGroupForFairValueOptionAxis=fbp_AmortizedCostMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_EligibleItemOrGroupForFairValueOptionAxis=fbp_MarketValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: