Amount of expense related to estimated loss for indemnifications.

No definition available.

Name:	cffi_ProvisionForLossOnIndemnification
Namespace Prefix:	cffi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The maximum recourse period for residential mortgage loans sold to third parties.

+ References

No definition available.

+ Details

Name:	cffi_RecoursePeriodForEarlyPaymentDefaultMaximum
Namespace Prefix:	cffi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum recourse period for early payment default on residential loans sold to third parties.

+ References

No definition available.

+ Details

Name:	cffi_RecoursePeriodForEarlyPaymentDefaultMinimum
Namespace Prefix:	cffi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349

+ Details

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

- Details

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

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_IndemnificationGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingent Liabilities - Other (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Commitments and Contingent Liabilities
Provision for indemnifications	$ 156,000	$ 0	$ 163,000	$ 0
Mortgage Banking Segment
Commitments and Contingent Liabilities
Recourse period for early payment default, minimum			90 days
Recourse period for early payment default, maximum			1 year
Indemnification reserve for recourse provisions
Commitments and Contingent Liabilities
Allowance for indemnifications	$ 2,640,000		$ 2,640,000		$ 2,480,000