CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Stockholders Equity [Abstract]
Common stock dividends, per share	$ 0.26	$ 0.26
Stock option plan, shares	12,353	17,362
Employee stock purchase plan, shares	6,912	4,431
Restricted stock, shares	1,514	7,288
Number of shares issued by the company, pursuant to WashingtonFirst acquisition	11,446,197,000