Parent Company Only Financial Statements - Schedule of Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash	$ 9,124	$ 6,834
Interest-bearing deposits in other banks	37,203	60,259
Other assets	13,992	10,300
Total assets	722,171	730,805
Liabilities and Shareholders' Equity
Junior subordinated debt	4,124	4,124
Other liabilities	12,075	7,256
Total liabilities	655,049	670,798
Shareholders’ Equity
Common stock, par value $3.13, and additional paid-in capital; authorized: 8,000,000 shares; issued and outstanding: 3,783,724 and 3,773,836 shares including 20,352 and 22,569 unvested shares, respectively	15,964	15,742
Retained earnings	49,787	44,803
Accumulated other comprehensive income (loss), net	1,371	(538)
Total shareholders’ equity	67,122	60,007	$ 56,142	$ 54,451
Total liabilities and shareholders’ equity	722,171	730,805
Fauquier Bankshares, Inc [Member]
Assets
Cash	598	282
Interest-bearing deposits in other banks	330	180
Investment in subsidiaries	70,313	63,410
Other assets	171	360
Total assets	71,412	64,232
Liabilities and Shareholders' Equity
Junior subordinated debt	4,124	4,124
Other liabilities	166	101
Total liabilities	4,290	4,225
Shareholders’ Equity
Common stock, par value $3.13, and additional paid-in capital; authorized: 8,000,000 shares; issued and outstanding: 3,783,724 and 3,773,836 shares including 20,352 and 22,569 unvested shares, respectively	15,964	15,742
Retained earnings	49,787	44,803
Accumulated other comprehensive income (loss), net	1,371	(538)
Total shareholders’ equity	67,122	60,007
Total liabilities and shareholders’ equity	$ 71,412	$ 64,232