LOAN PORTFOLIO - Loan Portfolio Held for Investment (Parenthetical) (Detail) - USD ($) $ in Billions	Mar. 31, 2016	Dec. 31, 2015
Financial Information [Line Items]
Commercian Loans Collaterized By Real Estate	$ 1.0	$ 1.0

Commercial loans secured by real estate (owner-occupied commercial loans secured by real estate) but are not dependent upon real estate for repayment.

No definition available.

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