Fair Value of Financial Instruments Nonrecurring Basis (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019
Assets measured on nonrecurring basis
OREO	$ 227,000				$ 94,000				$ 227,000
Losses on impaired loans charged through allowance for loan losses	1,136,000	$ 1,005,000	$ 626,000	$ (263,000)	975,000	$ 1,302,000	$ 1,188,000	$ 1,983,000
Nonrecurring Basis
Assets measured on nonrecurring basis
Losses on impaired loans charged through allowance for loan losses									1,600,000
Nonrecurring Basis | Level 3
Assets measured on nonrecurring basis
Impaired loans	29,100,000				24,129,000				29,100,000
OREO	227,000				$ 94,000				227,000
Nonrecurring Basis | Level 2
Assets measured on nonrecurring basis
Impaired loans, aggregate outstanding principal balance	$ 38,600,000								$ 38,600,000