Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total cost	$ 11,989	$ 10,420
Accumulated depreciation	(6,622)	(5,787)
Net book value	5,367	4,633
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total cost	6,505	5,518
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total cost	3,155	2,791
Equipment and Others
Property Plant And Equipment [Line Items]
Total cost	$ 2,329	$ 2,111