Loans, Allowance for Credit Losses, and Asset Quality Information - Schedule of Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	$ 10,463	$ 12,948
Nonaccrual Loans with an Allowance	18,206	21,748
Total Nonaccrual Loans	28,669	34,696
Commercial, financial, and agricultural
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	3,912	3,947
Nonaccrual Loans with an Allowance	7,446	8,205
Total Nonaccrual Loans	11,358	12,152
Real estate, commercial \| Real estate – construction, land development & other land loans
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	877	495
Nonaccrual Loans with an Allowance	120	137
Total Nonaccrual Loans	997	632
Real estate, commercial \| Real estate – mortgage – commercial and other
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	5,517	7,648
Nonaccrual Loans with an Allowance	5,992	8,583
Total Nonaccrual Loans	11,509	16,231
Real estate, mortgage \| Real estate – mortgage – residential (1-4 family) first mortgages
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	157	858
Nonaccrual Loans with an Allowance	3,203	4,040
Total Nonaccrual Loans	3,360	4,898
Real estate, mortgage \| Real estate – mortgage – home equity loans / lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	0	0
Nonaccrual Loans with an Allowance	1,340	694
Total Nonaccrual Loans	1,340	694
Consumer loans
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual Loans with No Allowance	0	0
Nonaccrual Loans with an Allowance	105	89
Total Nonaccrual Loans	$ 105	$ 89

Financing Receivable, Excluding Accrued Interest, Nonaccrual, With Allowance

No definition available.

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

- Definition

Amortized cost excluding accrued interest, of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_FixedRateResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: