Fair Values of Financial Instruments - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	$ 101,167	$ 101,560
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	4,472	4,500
U.S. government sponsored entities and agencies
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	13,926	8,998
U.S. agency mortgage-backed securities: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	20,758	25,626
U.S. agency collateralized mortgage obligations: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	21,924	24,706
State and political subdivision
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	29,240	27,608
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	9,030	7,932
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	1,817	2,190
Level 1
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	6,155	6,554
Level 1 | U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	4,472	4,500
Level 1 | U.S. government sponsored entities and agencies
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 1 | U.S. agency mortgage-backed securities: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 1 | U.S. agency collateralized mortgage obligations: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 1 | State and political subdivision
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 1 | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 1 | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	1,683	2,054
Level 2
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	86,880	94,870
Level 2 | U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 2 | U.S. government sponsored entities and agencies
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	13,926	8,998
Level 2 | U.S. agency mortgage-backed securities: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	20,758	25,626
Level 2 | U.S. agency collateralized mortgage obligations: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	21,924	24,706
Level 2 | State and political subdivision
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	29,240	27,608
Level 2 | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	1,032	7,932
Level 2 | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	8,132	136
Level 3 | U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3 | U.S. government sponsored entities and agencies
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3 | U.S. agency mortgage-backed securities: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3 | U.S. agency collateralized mortgage obligations: residential
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3 | State and political subdivision
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	0	0
Level 3 | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	7,998	0
Level 3 | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale	$ 134	$ 136