Condensed Financial Information (Parent Company Only) Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Expenses
Administrative and other													$ 7,115	$ 6,656	$ 7,080
Applicable income tax benefit													2,033	2,179	1,973
Net income	$ 2,345	$ 2,268	$ 2,139	$ 1,759	$ 1,927	$ 2,050	$ 2,017	$ 1,884	$ 1,885	$ 2,126	$ 1,919	$ 1,764	8,511	7,878	7,694
Parent Company [Member]
Revenues
Dividends - bank subsidiary - Union													5,050	5,100	4,950
Other income													40	25	52
Total revenues													5,090	5,125	5,002
Expenses
Interest													25	23	32
Stock based compensation expense													0	35	20
Administrative and other													441	351	401
Total expenses													466	409	453
Income before applicable income tax benefit and equity in undistributed net income of subsidiary													4,624	4,716	4,549
Applicable income tax benefit													(153)	(124)	(134)
Income before equity in undistributed net income of subsidiary													4,777	4,840	4,683
Equity in undistributed net income - Union													3,734	3,038	3,011
Net income													$ 8,511	$ 7,878	$ 7,694