Parent Company Only Financial Statements - Schedule of Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities
Net income	$ 5,877	$ 6,820	$ 6,135
Adjustments to reconcile net income to net cash provided by operating activities:
Issuance of vested restricted stock	175	90	90
Amortization of unearned compensation, net of forfeiture	328	250	214
(Increase) decrease in other assets	745	(4,731)	(1,065)
Increase in other liabilities	(822)	4,641	812
Net cash provided by operating activities	7,909	8,558	7,330
Cash Flows from Financing Activities
Repurchase of common stock	(24)	(21)	(8)
Cash dividends paid on common stock	(1,897)	(1,836)	(1,813)
Net cash provided by (used in) financing activities	137,954	(22,425)	79,714
Increase (decrease) in cash and cash equivalents	78,225	(20,769)	37,810
Cash and Cash Equivalents
Beginning	46,341	67,110	29,300
Ending	124,566	46,341	67,110
Fauquier Bankshares, Inc [Member]
Cash Flows from Operating Activities
Net income	5,877	6,820	6,135
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiaries	(4,051)	(4,745)	(4,883)
Issuance of vested restricted stock	175	90	90
Amortization of unearned compensation, net of forfeiture	254	153	133
(Increase) decrease in other assets		1	(33)
Increase in other liabilities	41	4	18
Net cash provided by operating activities	2,296	2,323	1,460
Cash Flows from Financing Activities
Repurchase of common stock	(24)	(21)	(8)
Cash dividends paid on common stock	(1,897)	(1,836)	(1,813)
Net cash provided by (used in) financing activities	(1,921)	(1,857)	(1,821)
Increase (decrease) in cash and cash equivalents	375	466	(361)
Cash and Cash Equivalents
Beginning	928	462	823
Ending	$ 1,303	$ 928	$ 462