Acquisitions - Pro-forma Financial Information of Combined Entities (Details) - HCB and FCB - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Total revenues, net of interest expense	$ 85,470	$ 82,634	$ 81,706
Net income	$ 13,029	$ 20,312	$ 18,915
Diluted earnings per share (in USD per share)	$ 1.09	$ 1.66	$ 1.54