Securities - Unrealized Loss Positions (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($)
Fair value
Less Than 12 Months, Fair Value	$ 28,423,000	$ 78,732,000
12 Months or More, Fair Value	109,110,000	45,109,000
Total Fair Value	137,533,000	123,841,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	162,000	489,000
12 Months or More, Unrealized Loss	2,504,000	867,000
Total Unrealized Loss	$ 2,666,000	1,356,000
Other information
Number of positions considered temporarily impaired | security	237
Other than temporary impairment loss	$ 0
U.S. government agencies and corporations
Fair value
Less Than 12 Months, Fair Value	997,000	2,972,000
12 Months or More, Fair Value	15,725,000	13,201,000
Total Fair Value	16,722,000	16,173,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	1,000	31,000
12 Months or More, Unrealized Loss	535,000	310,000
Total Unrealized Loss	536,000	341,000
Mortgage-backed securities
Fair value
Less Than 12 Months, Fair Value	17,934,000	57,116,000
12 Months or More, Fair Value	72,830,000	22,545,000
Total Fair Value	90,764,000	79,661,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	132,000	341,000
12 Months or More, Unrealized Loss	1,757,000	420,000
Total Unrealized Loss	1,889,000	761,000
Obligations of states and political subdivisions
Fair value
Less Than 12 Months, Fair Value	9,492,000	18,644,000
12 Months or More, Fair Value	20,555,000	9,363,000
Total Fair Value	30,047,000	28,007,000
Unrealized Loss
Less Than 12 Months, Unrealized Loss	29,000	117,000
12 Months or More, Unrealized Loss	212,000	137,000
Total Unrealized Loss	$ 241,000	$ 254,000
Standard & Poor's, A Rating | U.S. government agencies and corporations
Other information
Percentage of portfolio with rating	97.00%
Not A Rating Or Better | U.S. government agencies and corporations
Other information
Percentage of portfolio with rating in an unrealized loss positions	3.00%