Acquired equity interest on disposal of loans held for sale.

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Weighted average yield of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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The excess of the (1) par value of the trust preferred securities in the registrant's balance sheet over (2) the cash outflow to reacquire such securities.

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Trust Preferred Securities Winning Bid

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Variable rate trust preferred securities.

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Cash Flows between a transferor and a transferee attributable to purchases of previously transferred financial assets (or its underlying collateral) related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The increase (decrease) during the reporting period in the value of loans or securitized loans that are held with the intention to sell in the near future.

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Reflects the net positive or negative amount derived from subtracting from net proceeds of sale and the carrying amounts, net of allocated reserves, of financial assets transferred to third parties in transactions that qualify for sales treatment.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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The cash outflow to reacquire preferred stocks issued by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures.

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This is the principal amount outstanding for securitized loans only (across all types of loans).

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The cash inflow resulting from the sale of loans classified as held-for-sale, including proceeds from loans sold through mortgage securitization.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Description of qualitative information about the assumptions used to estimate fair value for servicing assets and servicing liabilities.

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NON-CONSOLIDATED VARIABLE INTEREST ENTITIES AND SERVICING ASSETS - additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended			12 Months Ended
	Feb. 16, 2011	Sep. 30, 2004	Apr. 30, 2004	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2016	Dec. 31, 2014	Dec. 31, 2018	Dec. 31, 2017
Servicing Liabilities At Fair Value [Line Items]
Principal amount of corporation serviced loans securitized through GNMA				$ 1,800,000
Gains Losses On Extinguishment Of Debt				0	$ 2,316
Interest Expense Accrued Trust Preferred Securities						$ 31,200
Carrying amount of servicing assets				27,431	26,135			$ 27,428	$ 25,255
Grantor Trust Fair Value				$ 31,553
Weighted-average yield				2.54%				2.55%
Loans sold to CPG				$ 0	558
Loans and Leases Receivable, Gross				$ 8,996,816	8,695,890			$ 8,858,123
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Qualitative Information				These sensitivities are hypothetical and should be used with caution. As the figures indicate, changes in fair value based on a 10% variation in assumptions generally cannot be extrapolated because the relationship between the change in assumption and the change in fair value may not be linear. Also, in this table, the effect of a variation in a particular assumption on the fair value of the servicing asset is calculated without changing any other assumption; in reality, changes in one factor may result in changes in another (for example, increases in market interest rates may result in lower prepayments), which may magnify or counteract the sensitivities.
Percentage Of Variation In Assumptions				10.00%
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Servicing Liabilities At Fair Value [Line Items]
Debt Instrument Description Of Variable Rate Basis				90-day LIBOR
Carrying amount of servicing assets				$ 18,800
Grantor Trust Fair Value				$ 13,400
Weighted-average yield				4.68%
Fbp Statutory Trust One [Member]
Servicing Liabilities At Fair Value [Line Items]
Trust Preferred Securities Repurchases					$ 23,800
Trust Preferred Securities Winning Bid					90.00%
Trust Preferred Securties Discount					10.00%
Fbp Statutory Trust One [Member] \| Trust Preferred Securities Subject to Mandatory Redemption [Member]
Servicing Liabilities At Fair Value [Line Items]
Gains Losses On Extinguishment Of Debt					$ 2,300
Cpg Gs [Member]
Servicing Liabilities At Fair Value [Line Items]
Debt Instrument, Maturity Date, Description				three-year maturity
Loans sold to CPG	$ 269,300
Cash realized on sale of loan	$ 88,500
Acquired Equity interest on disposal of loans held for sale	35.00%
Loans and Leases Receivable, Gross	$ 136,100			$ 4,500
Carrying amount of the Bank investment in CPG/GS							$ 0
Cpg Gs [Member] \| Prlp [Member]
Servicing Liabilities At Fair Value [Line Items]
Payment to be made on pro rata basis				35.00%
Cpg Gs [Member] \| FirstBank [Member]
Servicing Liabilities At Fair Value [Line Items]
Payment to be made on pro rata basis				65.00%
Maximum [Member]
Servicing Liabilities At Fair Value [Line Items]
Percentage Of Variation In Assumptions				20.00%
Minimum [Member]
Servicing Liabilities At Fair Value [Line Items]
Percentage Of Variation In Assumptions				10.00%
Minimum [Member] \| Cpg Gs [Member] \| Prlp [Member]
Servicing Liabilities At Fair Value [Line Items]
Percentage Of Priority Interest To Be Received On Invested Capital				12.00%
Variable Rate Demand Obligation [Member] \| Junior Subordinated Deferrable Debentures [Member]
Servicing Liabilities At Fair Value [Line Items]
Debt Instrument, Maturity Date, Description				The Junior Subordinated Deferrable Debentures issued by the Corporation in April 2004 and September 2004 mature on June 17, 2034 and September 20, 2034, respectively; however, under certain circumstances, the maturity of Junior Subordinated Deferrable Debentures may be shortened (such shortening would result in a mandatory redemption of the variable-rate TRuPs).
Variable Rate Demand Obligation [Member] \| Fbp Statutory Trust One [Member]
Servicing Liabilities At Fair Value [Line Items]
Variable rate trust preferred securities			$ 100,000
Proceeds of the issuance, together with proceeds of the purchase			3,100
Variable Rate Demand Obligation [Member] \| Fbp Statutory Trust One [Member] \| Junior Subordinated Deferrable Debentures [Member]
Servicing Liabilities At Fair Value [Line Items]
Principal amount of corporation's junior subordinated deferrable debentures			$ 103,100
Fbp Statutory Trust Two [Member] \| Variable Rate Demand Obligation [Member]
Servicing Liabilities At Fair Value [Line Items]
Variable rate trust preferred securities		$ 125,000
Proceeds of the issuance, together with proceeds of the purchase		3,900
Fbp Statutory Trust Two [Member] \| Variable Rate Demand Obligation [Member] \| Junior Subordinated Deferrable Debentures [Member]
Servicing Liabilities At Fair Value [Line Items]
Principal amount of corporation's junior subordinated deferrable debentures		$ 128,900