CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - UNAUDITED - (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Stockholders Equity [Abstract]
Common stock dividends, per share	$ 0.28	$ 0.26
Stock option plan, shares	6,755	12,353
Employee stock purchase plan, shares	7,662	6,912
Restricted stock, shares	11,959	1,514
Number of shares issued by the company, pursuant to WashingtonFirst acquisition		11,446,197