Fair Value of Assets and Liabilities - Financial Assets Measured at Fair Value on Non-Recurring Basis (Details) - Nonrecurring $ in Thousands	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	$ 370	$ 348
Impaired loans, net
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	102	102
Other real estate owned, net
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	268	246
Level 3
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	370	348
Level 3 | Impaired loans, net
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	$ 102	102
Impaired loans, input	0.30
Impaired loans, net, valuation technique	cffi:ValuationTechniqueAppraisalsMember
Impaired loans, net, measurement input	us-gaap:MeasurementInputDiscountRateMember
Level 3 | Other real estate owned, net
Fair value assets and liabilities - Nonrecurring Basis
Financial assets measured at fair value on a non-recurring basis	$ 268	$ 246
Other real estate owned, net, valuation technique	cffi:ValuationTechniqueAppraisalsMember
Other real estate owned, net, measurement input	us-gaap:MeasurementInputDiscountRateMember
Level 3 | Other real estate owned, net | Minimum
Fair value assets and liabilities - Nonrecurring Basis
Other real estate owned, input	0.33
Level 3 | Other real estate owned, net | Maximum
Fair value assets and liabilities - Nonrecurring Basis
Other real estate owned, input	0.75