OTHER NON- INTEREST EXPENSES- Detail of other non-interest expenses (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Non Interest Expenses [Abstract]
Supplies and printing	$ 2,140fbp_SuppliesAndPrintingExpenses	$ 3,014fbp_SuppliesAndPrintingExpenses	$ 2,811fbp_SuppliesAndPrintingExpenses
Contigency Adjustment	0fbp_ContigencyAdjustment	0fbp_ContigencyAdjustment	2,489fbp_ContigencyAdjustment
Reserve (release) for off-balance sheet exposures	(653)fbp_ProvisionForOffBalanceSheetItems	(443)fbp_ProvisionForOffBalanceSheetItems	(1,914)fbp_ProvisionForOffBalanceSheetItems
Other	10,253us-gaap_OtherGeneralExpense	15,632us-gaap_OtherGeneralExpense	13,324us-gaap_OtherGeneralExpense
Amortization Of Intangible Assets	4,943us-gaap_AmortizationOfIntangibleAssets	6,078us-gaap_AmortizationOfIntangibleAssets	3,306us-gaap_AmortizationOfIntangibleAssets
Information Technology And Data Processing	1,619	1,601	1,568
Losses On Sales Of Non Real Estate	737fbp_LossesOnSalesOfNonRealEstate	263fbp_LossesOnSalesOfNonRealEstate	338fbp_LossesOnSalesOfNonRealEstate
Contingency for attorney's fees	0fbp_ContingencyForAttorneysFees	2,500fbp_ContingencyForAttorneysFees	0fbp_ContingencyForAttorneysFees
Total	$ 19,039us-gaap_OtherNoninterestExpense	$ 28,645us-gaap_OtherNoninterestExpense	$ 21,922us-gaap_OtherNoninterestExpense

Contigency reserve related to mortgage credits.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

loss contingency for attorneys fees awarded to the other party Related to Lehman.

+ References

No definition available.

+ Details

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- Definition

The net loss resulting from sales and other disposals of non real estate owned, decreases in the valuation allowance for the foreclosed property, and write-downs of other non real estate owned after acquisition or physical possession.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Details

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- Definition

Accrued liability to reflect obligations, contingent liabilities, and other exposures relating to off-balance sheet arrangements such as unfunded loan commitments, contractual obligations, recourse from loans securitized, and variable interest entities.

+ References

No definition available.

+ Details

Name:	fbp_ProvisionForOffBalanceSheetItems
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of expense in the period for supplies and printing.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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- Definition

The amount of expenses incurred in the period for information technology and data processing products and services.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of general expenses not normally included in Other Operating Costs and Expenses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.6)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 6

-Article 5

+ Details

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- Definition

Other noninterest expenses that are not separately presented in any other noninterest expense category.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.14)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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