Acquisition of First Priority Financial Corp. (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Net interest income after loan loss provision	$ 17,202	$ 15,811	$ 51,688	$ 37,978
Noninterest income	3,003	2,171	7,926	5,441
Noninterest expense	$ 14,683	15,270	$ 43,782	36,259
First Priority Financial Corp. [Member]
Business Acquisition [Line Items]
Net interest income after loan loss provision		17,373		48,914
Noninterest income		2,220		5,754
Noninterest expense		13,543		41,352
Net income		$ 5,502		$ 10,995
Net income per common share		$ 0.70		$ 1.49