Condensed Financial Information (Parent Company Only) Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 2,759	$ 2,738	$ 2,530	$ 2,621	$ (436)	$ 2,311	$ 2,450	$ 2,747	$ 10,648	$ 7,072
Adjustments to reconcile net income to net cash provided by operating activities
Decrease (increase) in other assets									(110)	(685)
Net cash provided by operating activities									11,776	16,761
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from sales of other investments									46	44
Purchases of other investments									(180)	(79)
Proceeds of Company-owned life insurance death benefit									0	307
Net cash provided by investing activities									(49,061)	(67,981)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends paid									(5,501)	(5,328)
Issuance of common stock									44	0
Purchase of treasury stock									(13)	(107)
Net cash used in financing activities									51,130	50,001
Net decrease in cash									13,845	(1,219)
Dividends paid on Common Stock [Abstract]
Dividends declared									5,540	5,358
Dividends reinvested									(39)	(30)
Dividends paid on Common Stock									5,501	5,328
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									10,648	7,072
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed net income of Union									(5,138)	(1,541)
Decrease (increase) in other assets									55	(205)
Decrease in other liabilities									(137)	(233)
Net cash provided by operating activities									5,428	5,093
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from sales of other investments									47	44
Purchases of other investments									(7)	(12)
Proceeds of Company-owned life insurance death benefit									0	281
Net cash provided by investing activities									40	313
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends paid									(5,501)	(5,328)
Issuance of common stock									44	0
Purchase of treasury stock									(13)	(107)
Net cash used in financing activities									(5,470)	(5,435)
Net decrease in cash									(2)	(29)
CASH
Beginning of year				$ 48				$ 77	48	77
End of year	$ 46				$ 48				46	48
Supplemental Disclosures of Cash Flow Information
Interest paid									16	18
Dividends paid on Common Stock [Abstract]
Dividends declared									5,540	5,358
Dividends reinvested									(39)	(30)
Dividends paid on Common Stock									$ 5,501	$ 5,328