Fair Value (Additional Information) (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-Sale, at Fair Value		$ 19,156,000		$ 19,156,000		$ 4,263,000
Contractual principal balance of loan held for sale		18,786,000		18,786,000		4,231,000
Difference in amount of loan held for sale		370,000		370,000		32,000
Impaired loans, carrying amount	[1]	7,870,000		7,870,000		6,757,000
Valuation allowance for impaired loans		3,417,000		3,417,000		1,826,000
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
90 Days Past Due or Non-accrual
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-Sale, at Fair Value		0		0		0
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		849,445,000		849,445,000		812,611,000
Loans Held-for-Sale, at Fair Value		19,156,000		19,156,000		4,263,000
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		4,030,000		4,030,000		4,991,000
Loans Held-for-Sale, at Fair Value		0		0		0
Obligations of State and Political Subdivisions | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities		317,472,000		317,472,000		294,533,000
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		4,030,000		4,030,000		4,991,000
Commercial and Industrial and Commercial Real Estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, carrying amount		6,236,000		6,236,000		6,561,000
Valuation allowance for impaired loans		3,060,000		3,060,000		1,823,000
Increase (decrease) to provision for loan losses		$ 1,510,000	$ 190,000	$ 1,237,000	$ (640,000)	$ (411,000)

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