Fair Value (Additional Information) (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, carrying amount	[1]					$ 7,229,000
Valuation allowance for impaired loans						3,371,000
Other real estate carried at fair value less cost to sell		$ 0		$ 0		0
Other real estate, adjustments to carrying value less costs to charged to earnings		0	$ 0	0	$ 0	0
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		1,036,910,000		1,036,910,000		854,825,000
Significant Unobservable  Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		497,000		497,000		4,021,000
Loans Held-for-sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gains/(losses) from changes in fair value included in earnings		233,000	112,000	330,000	339,000
Obligations of State and Political Subdivisions | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		514,012,000		514,012,000		324,300,000
Gains/(losses) from changes in fair value included in other comprehensive income		(3,000)	$ (1,000)	(26,000)	$ (16,000)
Obligations of State and Political Subdivisions | Significant Unobservable  Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		497,000		497,000		4,021,000
Collateral-dependent loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, carrying amount		22,621,000		22,621,000		5,574,000
Valuation allowance for impaired loans		7,344,000		7,344,000		2,971,000
Collateral-dependent loans | Individually Analyzed Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Increase (decrease) in allowance for loan losses		$ 136,000		$ 1,822,000		$ (1,149,000)

[1] Unpaid Principal Balance is the remaining contractual payments gross of partial charge-offs and discounts.