Name:	fbnc_DepositsOther
Namespace Prefix:	fbnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Funding Commitment, Remaining Amount Committed

No definition available.

Name:	fbnc_FundingCommitmentRemainingAmountCommitted
Namespace Prefix:	fbnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The threshold for marketable securities issued to any one guarantor.

No definition available.

Name:	fbnc_MarketableSecuritiesToAnyOneIssuerOrGuarantorThreshold
Namespace Prefix:	fbnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Number Of Counties With Branch Locations

No definition available.

Name:	fbnc_NumberOfCountiesWithBranchLocations
Namespace Prefix:	fbnc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation.

No definition available.

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

This item represents a non-contingent liability for the fair value of an obligation to stand ready to perform over the term of a guaranty issued in the event that specified triggering events or conditions occur.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15)
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 25
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118943535&loc=d3e11019-110243

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 25
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118943535&loc=d3e11049-110243

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

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_FinancialInstrumentAxis=fbnc_FederalHomeLoanBankAtlantaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FinancialInstrumentAxis=fbnc_FederalReserveBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FinancialInstrumentAxis=fbnc_PCBBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=stpr_NC
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: