Goodwill and Other Intangibles and Mortgage Servicing Rights - Mortgage servicing rights (Details) - Mortgage Servicing Rights - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Mortgage servicing rights (MSR) asset:
MSR asset at beginning of year	$ 5,919,000	$ 3,749,000
Capitalized MSR	559,000	2,876,000
MSR asset acquired	0	160,000
Amortization during the period	(284,000)	(866,000)
MSR asset at end of period	6,194,000	5,919,000
Valuation Allowance:
Valuation allowance at beginning of year	0	0
Additions	(175,000)	0
Valuation allowance at end of period	(175,000)	0
MSR asset, net	6,019,000	5,919,000
Fair value of MSR asset at end of period	8,807,000	8,420,000
Residential mortgage loans serviced for others	$ 890,162,000	$ 847,756,000
Net book value of MSR asset to loans serviced for others	0.68%	0.70%