Fair Value of Assets and Liabilities - Financial Assets Measured at Fair Value on Non-Recurring Basis (Details)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Impaired loans, net
Fair value assets and liabilities - Nonrecurring Basis
Total assets measured at fair value	$ 0	$ 0
Nonrecurring
Fair value assets and liabilities - Nonrecurring Basis
Total assets measured at fair value	22,000	72,000
Nonrecurring | Other real estate owned, net
Fair value assets and liabilities - Nonrecurring Basis
Total assets measured at fair value	22,000	72,000
Level 3 | Nonrecurring
Fair value assets and liabilities - Nonrecurring Basis
Total assets measured at fair value	22,000	72,000
Level 3 | Nonrecurring | Other real estate owned, net
Fair value assets and liabilities - Nonrecurring Basis
Total assets measured at fair value	$ 22,000	$ 72,000
Other real estate owned, net, valuation technique	cffi:ValuationTechniqueAppraisalsMember	cffi:ValuationTechniqueAppraisalsMember
Other real estate owned, net, measurement input	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Level 3 | Nonrecurring | Other real estate owned, net | Minimum
Fair value assets and liabilities - Nonrecurring Basis
Other real estate owned, input	0.75	0.75
Level 3 | Nonrecurring | Other real estate owned, net | Maximum
Fair value assets and liabilities - Nonrecurring Basis
Other real estate owned, input	0.75	0.80
Level 3 | Nonrecurring | Other real estate owned, net | Weighted Average
Fair value assets and liabilities - Nonrecurring Basis
Other real estate owned, input		0.79