Share Based Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2017	May 19, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)	$ 0.835	$ 0.835
Total compensation cost	$ 442	$ 335	$ 332
Cash received from options exercised	2,300	532	380
Total intrinsic value of options exercised	$ 2,000	$ 340	$ 239
Weighted average grant date fair value, options granted (in usd per share)	$ 6.16	$ 4.12	$ 2.85
Total unrecognized compensation cost, non-vested shares	$ 1,100
Weighted average period for cost recognition	1 year 7 months 6 days
Access National Corporation 2009 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, reserved (in shares)					975,000
Common stock, par value (in dollars per share)					$ 0.835
Expiration period for options granted	5 years
Access National Corporation 2017 Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, reserved (in shares)				1,500,000.0
Common stock, par value (in dollars per share)				$ 0.835