INVESTMENT SECURITIES - Narratives (Detail)	Sep. 30, 2017 minimumcreditscore
Disclosure Investment Securities Additional Information [Abstract]
Minimum Credit Score	700

Disclosure Investment Securities Additional Information [Abstract]

No definition available.

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