PARENT COMPANY FINANCIAL INFORMATION (Schedule of condensed statements of income of Southern National Bancorp of Virginia, Inc.) (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	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Total interest and dividend income	$ 29,354	$ 30,474	$ 30,393	$ 30,303	$ 31,150	$ 30,054	$ 29,683	$ 28,020	$ 120,524	$ 118,907	$ 83,570
Interest on junior subordinated debt									589	575	253
Interest on senior subordinated notes									2,847	2,847	2,194
Merger expenses											9,426
Other operating expenses									10,169	7,423	5,707
Income before income taxes	10,232	11,225	10,263	7,524	10,824	11,061	11,060	10,360	39,244	43,305	15,572
Income tax benefit									(6,077)	(9,614)	(13,147)
Net income	$ 8,964	$ 8,864	$ 9,319	$ 6,020	$ 7,704	$ 8,861	$ 8,867	$ 8,259	33,167	33,691	2,425
Southern National | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Cash dividends received from Sonabank									13,300	8,000	4,900
Interest on deposits with subsidiary											3
Total interest and dividend income									13,300	8,000	4,903
Interest on junior subordinated debt									589	575	253
Interest on senior subordinated notes									2,847	2,847	2,194
Merger expenses											2,812
Other operating expenses									726	765	478
Total expense									4,162	4,187	5,737
Income before income taxes									9,138	3,813	(834)
Income tax benefit									862	872	1,196
Equity in undistributed net income of Sonabank									23,167	29,006	2,063
Net income									$ 33,167	$ 33,691	$ 2,425