Parent Company Only Financial Statements - Schedule of Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income
Interest income	$ 26,192	$ 26,398	$ 24,291
Total interest income	28,312	29,170	26,698
Expenses
Interest expense	2,541	4,520	3,233
Directors' fees	375	326	329
Miscellaneous	3,565	3,427	3,414
Total noninterest expenses	23,520	22,454	22,151
Income before income taxes	6,944	7,824	6,881
Income tax benefit	1,067	1,004	746
Net Income	5,877	6,820	6,135
Fauquier Bankshares, Inc [Member]
Income
Interest income	2	9	4
Dividends from subsidiaries	2,423	2,654	1,813
Total interest income	2,425	2,663	1,817
Expenses
Interest expense	186	199	199
Legal and professional fees	197	184	149
Directors' fees	241	218	218
Miscellaneous	282	285	288
Total noninterest expenses	906	886	854
Income before income taxes	1,519	1,777	963
Income tax benefit	(307)	(298)	(289)
Income before equity in undistributed net income of subsidiaries	1,826	2,075	1,252
Equity in undistributed net income of subsidiaries	4,051	4,745	4,883
Net Income	$ 5,877	$ 6,820	$ 6,135