Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 28, 2020	Jun. 30, 2019
Entity Information [Line Items]
Entity Registrant Name	UNION BANKSHARES INC
Entity Central Index Key	0000706863
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		4,473,186
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 145,240,175