Banking Premises and Equipment - Summary of Cost and Accumulated Depreciation and Amortization of Property, Leasehold Improvements and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 33,169	$ 24,988
Accumulated depreciation and amortization	(18,413)	(16,410)
Total	14,756	8,578
Land
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	1,116	1,116
Building and leasehold improvements
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 17,817	12,175
Building and leasehold improvements | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years
Building and leasehold improvements | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	30 years
Equipment, including vaults
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 13,686	11,613
Equipment, including vaults | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years
Equipment, including vaults | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	20 years
Work in process
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 550	$ 84