Commitments, Credit Risk, and Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Credit Risk
Rental expenses	$ 1,800,000	$ 1,100,000	$ 764,000
Due within one year	1,564,000
Due in one year to two years	1,383,000
Due in two years to three years	1,208,000
Due in three years to four years	1,208,000
Due in four years to five years	1,003,000
Thereafter	1,551,000
Total minimum lease payments	$ 7,917,000
Minimum
Commitments and Credit Risk
Lease period	1 year
Maximum
Commitments and Credit Risk
Lease period	10 years