Securities - Unrealized Loss Positions (Details)	9 Months Ended
	Sep. 30, 2019 USD ($) security	Dec. 31, 2018 USD ($)
Fair value
Less Than 12 Months, Fair Value	$ 24,047,000	$ 28,423,000
12 Months or More, Fair Value	25,173,000	109,110,000
Total Fair Value	49,220,000	137,533,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	29,000	162,000
12 Months or More, Unrealized Loss	123,000	2,504,000
Total Unrealized Loss	$ 152,000	2,666,000
Other information
Number of positions considered temporarily impaired | security	85
Debt securities considered temporarily impaired	$ 49,220,000	137,533,000
Other than temporary impairment	0
U.S. government agencies and corporations
Fair value
Less Than 12 Months, Fair Value	7,442,000	997,000
12 Months or More, Fair Value	8,821,000	15,725,000
Total Fair Value	16,263,000	16,722,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	1,000	1,000
12 Months or More, Unrealized Loss	25,000	535,000
Total Unrealized Loss	26,000	536,000
Other information
Debt securities considered temporarily impaired	16,263,000	16,722,000
Mortgage-backed securities
Fair value
Less Than 12 Months, Fair Value	10,828,000	17,934,000
12 Months or More, Fair Value	13,762,000	72,830,000
Total Fair Value	24,590,000	90,764,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	22,000	132,000
12 Months or More, Unrealized Loss	89,000	1,757,000
Total Unrealized Loss	111,000	1,889,000
Other information
Debt securities considered temporarily impaired	24,590,000	90,764,000
Obligations of states and political subdivisions
Fair value
Less Than 12 Months, Fair Value	5,777,000	9,492,000
12 Months or More, Fair Value	2,590,000	20,555,000
Total Fair Value	8,367,000	30,047,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	6,000	29,000
12 Months or More, Unrealized Loss	9,000	212,000
Total Unrealized Loss	15,000	241,000
Other information
Debt securities considered temporarily impaired	$ 8,367,000	$ 30,047,000
Standard & Poor's, A Rating [Member]
Other information
Percentage of portfolio with rating	95.00%
Percentage of portfolio with rating in an unrealized loss positions	97.00%
Not A Rating Or Better
Other information
Percentage of portfolio with rating	3.00%