Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Assets
Securities available for sale	$ 393,331	$ 369,995
Loan yield maintenance provisions	653	685	$ 789
Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	393,331	369,995
Loan yield maintenance provisions	653	685
Corporate bonds
Financial Assets
Securities available for sale	1,234	1,339
Corporate bonds | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	1,234	1,339
Collateralized mortgage obligations
Financial Assets
Securities available for sale	17,121	20,693
Collateralized mortgage obligations | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	17,121	20,693
Small Business Administration
Financial Assets
Securities available for sale	14,212	16,706
Small Business Administration | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	14,212	16,706
U.S. Treasury and U.S. government sponsored entities
Financial Assets
Securities available for sale	8,917	5,921
U.S. Treasury and U.S. government sponsored entities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	8,917	5,921
State and political subdivisions
Financial Assets
Securities available for sale	191,003	155,303
State and political subdivisions | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	191,003	155,303
Mortgage-backed securities - residential
Financial Assets
Securities available for sale	160,450	169,682
Mortgage-backed securities - residential | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	160,450	169,682
Equity securities
Financial Assets
Securities available for sale	394	351
Equity securities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	394	351
Interest rate swaps | Fair Value, Measurements, Recurring
Financial Liabilities
Derivative liabilities	653	685
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	394	351
Loan yield maintenance provisions	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Collateralized mortgage obligations | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Small Business Administration | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury and U.S. government sponsored entities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | State and political subdivisions | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities - residential | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	394	351
Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps | Fair Value, Measurements, Recurring
Financial Liabilities
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	392,929	369,632
Loan yield maintenance provisions	653	685
Significant Other Observable Inputs (Level 2) | Corporate bonds | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	1,234	1,339
Significant Other Observable Inputs (Level 2) | Collateralized mortgage obligations | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	17,121	20,693
Significant Other Observable Inputs (Level 2) | Small Business Administration | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	14,212	16,706
Significant Other Observable Inputs (Level 2) | U.S. Treasury and U.S. government sponsored entities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	8,917	5,921
Significant Other Observable Inputs (Level 2) | State and political subdivisions | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	191,003	155,303
Significant Other Observable Inputs (Level 2) | Mortgage-backed securities - residential | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	160,442	169,670
Significant Other Observable Inputs (Level 2) | Equity securities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Other Observable Inputs (Level 2) | Interest rate swaps | Fair Value, Measurements, Recurring
Financial Liabilities
Derivative liabilities	653	685
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	8	12
Loan yield maintenance provisions	0	0
Significant Unobservable Inputs (Level 3) | Corporate bonds | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Collateralized mortgage obligations | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Small Business Administration | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | U.S. Treasury and U.S. government sponsored entities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | State and political subdivisions | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Mortgage-backed securities - residential | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	8	12
Significant Unobservable Inputs (Level 3) | Equity securities | Fair Value, Measurements, Recurring
Financial Assets
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Interest rate swaps | Fair Value, Measurements, Recurring
Financial Liabilities
Derivative liabilities	$ 0	$ 0