Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Commitments (Details) - USD ($)	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Company's contractual commitments due to letters of credit
Total letters of credit	$ 15,458,000			$ 16,801,000
Provision for Unfunded Commitments	980,000	$ 734,000	$ 2,500,000
Fixed [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	685,000			910,000
Variable [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	14,773,000			15,891,000
Commitments to Extend Credit to Borrowers [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	15,391,000			16,734,000
Commitments to Extend Credit to Borrowers [Member] | Fixed [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	685,000			910,000
Commitments to Extend Credit to Borrowers [Member] | Variable [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	14,706,000			15,824,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	9,210,000			9,951,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Fixed [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	329,000			339,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Variable [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	8,881,000			9,612,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	6,181,000			6,783,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Fixed [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	356,000			571,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Variable [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	5,825,000			6,212,000
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	67,000			67,000
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member] | Variable [Member]
Company's contractual commitments due to letters of credit
Total letters of credit	67,000			67,000
Letter of Credit [Member] | Unused lines of Credit [Member]
Company's contractual commitments due to letters of credit
Loan commitments	419,037,000			431,468,000
Letter of Credit [Member] | Unused lines of Credit [Member] | Fixed [Member]
Company's contractual commitments due to letters of credit
Loan commitments	93,875,000			111,348,000
Letter of Credit [Member] | Unused lines of Credit [Member] | Variable [Member]
Company's contractual commitments due to letters of credit
Loan commitments	$ 325,162,000			$ 320,120,000
Revision of Prior Period, Adjustment [Member] | Accounting Standards Update 2016-13
Company's contractual commitments due to letters of credit
Provision for Unfunded Commitments			$ 1,700,000