Condensed Financial Information (Parent Company Only) Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Investment securities available-for-sale	$ 65,556	$ 54,110
Other assets	9,391	8,175
Total assets	691,381	628,879
LIABILITIES
Other liabilities	5,847	5,339
Total liabilities	635,102	575,311
STOCKHOLDERS' EQUITY
Common stock, $2.00 par value; 7,500,000 shares authorized; 4,936,652 shares issued at December 31, 2016 and 4,931,796 shares issued at December 31, 2015	9,874	9,864
Additional-paid-in capital	620	501
Retained earnings	53,086	49,524
Treasury stock at cost; 474,517 shares at December 31, 2016 and 474,619 shares at December 31, 2015	(4,022)	(4,019)
Accumulated other comprehensive loss	(3,279)	(2,302)
Total stockholders' equity	56,279	53,568	$ 51,434	$ 49,820
Total liabilities and stockholders' equity	691,381	628,879
Parent Company [Member]
ASSETS
Cash	49	57
Investment securities available-for-sale	97	110
Investment in subsidiary - Union	56,007	53,184
Other assets	805	941
Total assets	56,958	54,292
LIABILITIES
Other liabilities	679	724
Total liabilities	679	724
STOCKHOLDERS' EQUITY
Common stock, $2.00 par value; 7,500,000 shares authorized; 4,936,652 shares issued at December 31, 2016 and 4,931,796 shares issued at December 31, 2015	9,874	9,864
Additional-paid-in capital	620	501
Retained earnings	53,086	49,524
Treasury stock at cost; 474,517 shares at December 31, 2016 and 474,619 shares at December 31, 2015	(4,022)	(4,019)
Accumulated other comprehensive loss	(3,279)	(2,302)
Total stockholders' equity	56,279	53,568
Total liabilities and stockholders' equity	$ 56,958	$ 54,292