Loans - Past Due Status (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Loans on nonaccrual status
Total Past Due	$ 7,028	$ 11,126
Current	1,374,846	1,334,921
Total Loans	1,387,244	1,352,406
90+ days past due and accruing		145
Additional disclosure for nonaccrual loans
Current, nonaccrual status	2,770	2,860
Nonaccrual loans, 30-59 days past due		115
Nonaccrual loans, 90+ days past due	283	433
PCI
Loans on nonaccrual status
PCI	5,370	6,359
30-59 Days Past Due
Loans on nonaccrual status
Total Past Due	5,672	9,427
60-89 Days Past Due
Loans on nonaccrual status
Total Past Due	1,073	1,121
90+ Days Past Due
Loans on nonaccrual status
Total Past Due	283	578
Real estate - residential mortgage
Loans on nonaccrual status
Total Past Due	1,012	1,430
Current	216,373	215,395
Total Loans	218,189	218,298
90+ days past due and accruing		145
Real estate - residential mortgage \| PCI
Loans on nonaccrual status
PCI	804	1,473
Real estate - residential mortgage \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due	560	1,100
Real estate - residential mortgage \| 60-89 Days Past Due
Loans on nonaccrual status
Total Past Due	307	154
Real estate - residential mortgage \| 90+ Days Past Due
Loans on nonaccrual status
Total Past Due	145	176
Real estate - construction
Loans on nonaccrual status
Total Loans	53,921	62,147
Commercial, financial and agricultural
Loans on nonaccrual status
Total Loans	730,177	700,215
Equity lines
Loans on nonaccrual status
Total Past Due	72	52
Current	43,675	48,334
Total Loans	43,782	48,466
Equity lines \| PCI
Loans on nonaccrual status
PCI	35	80
Equity lines \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due		52
Equity lines \| 60-89 Days Past Due
Loans on nonaccrual status
Total Past Due	72
Consumer
Loans on nonaccrual status
Total Past Due		2
Current	8,261	10,978
Total Loans	8,302	11,028
Consumer \| PCI
Loans on nonaccrual status
PCI	41	48
Consumer \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due		2
Consumer finance
Loans on nonaccrual status
Total Past Due	5,896	9,618
Current	326,977	302,634
Total Loans	332,873	312,252
Consumer finance \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due	5,064	8,249
Consumer finance \| 60-89 Days Past Due
Loans on nonaccrual status
Total Past Due	694	967
Consumer finance \| 90+ Days Past Due
Loans on nonaccrual status
Total Past Due	138	402
Construction lending \| Real estate - construction
Loans on nonaccrual status
Current	38,729	49,659
Total Loans	38,729	49,659
Consumer lot lending \| Real estate - construction
Loans on nonaccrual status
Current	15,192	12,488
Total Loans	15,192	12,488
Commercial real estate lending \| Commercial, financial and agricultural
Loans on nonaccrual status
Total Past Due	48
Current	477,676	437,145
Total Loans	482,214	441,903
Commercial real estate lending \| Commercial, financial and agricultural \| PCI
Loans on nonaccrual status
PCI	4,490	4,758
Commercial real estate lending \| Commercial, financial and agricultural \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due	48
Land acquisition and development lending \| Commercial, financial and agricultural
Loans on nonaccrual status
Current	31,671	37,724
Total Loans	31,671	37,724
Builder line lending \| Commercial, financial and agricultural
Loans on nonaccrual status
Current	28,233	18,194
Total Loans	28,233	18,194
Commercial business lending \| Commercial, financial and agricultural
Loans on nonaccrual status
Total Past Due		24
Current	188,059	202,370
Total Loans	$ 188,059	202,394
Commercial business lending \| Commercial, financial and agricultural \| 30-59 Days Past Due
Loans on nonaccrual status
Total Past Due		$ 24

Financing receivables that are less than 60 days past due but more than 29 days past due that are in nonaccrual status.

No definition available.

Name:	cffi_FinancingReceivableRecordedInvestment30To59DaysPastDueNonaccrualStatus
Namespace Prefix:	cffi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are current or less than 30 days past due.

+ References

No definition available.

+ Details

Name:	cffi_FinancingReceivableRecordedInvestmentCurrentAnd1To29DaysPastDue
Namespace Prefix:	cffi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are current and less than 30 days past due that are in nonaccrual status.

+ References

No definition available.

+ Details

Name:	cffi_FinancingReceivableRecordedInvestmentCurrentAnd1To29DaysPastDueNonaccrualStatus
Namespace Prefix:	cffi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are equal to or greater than 90 days past due that are in nonaccrual status.

+ References

No definition available.

+ Details

Name:	cffi_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDueNonaccrualStatus
Namespace Prefix:	cffi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of financing receivable 90 days or more past due and still accruing.

+ 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 (c)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount of financing receivable past due.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919253-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953401-111524

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

+ Details

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

- Definition

Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

+ Details

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

- Details

Name:	us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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