Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total cost	$ 13,384	$ 12,778
Accumulated depreciation	(9,185)	(8,234)
Net book value	4,199	4,544
Leasehold improvements
Property Plant And Equipment [Line Items]
Total cost	7,095	6,878
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total cost	3,377	3,307
Equipment and others
Property Plant And Equipment [Line Items]
Total cost	$ 2,912	$ 2,593