Condensed Financial Statements of Parent Company - Condensed Financial Statements Company (Condensed Statements of Income and Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements Captions [Line Items]
Income before income taxes	$ 5,330	$ 5,054	$ 3,388	$ 4,462	$ 5,515	$ 5,238	$ 5,065	$ 6,258	$ 18,234	$ 22,076	$ 19,457
Income tax benefit	1,513	1,459	972	1,163	1,334	1,238	1,229	1,518	5,107	5,319	5,204
Net income	$ 3,817	$ 3,595	$ 2,416	$ 3,299	$ 4,181	$ 4,000	$ 3,836	$ 4,740	13,127	16,757	14,253
Other comprehensive income (loss), net of tax									652	736	(198)
Comprehensive income									13,779	17,493	14,055
Parent Company
Condensed Financial Statements Captions [Line Items]
Other expense									1,047	1,011	134
Income before income taxes									(1,047)	(1,011)	(134)
Income tax benefit									(275)	(288)	(40)
Equity in undistributed subsidiary income									13,899	17,480	14,347
Net income									13,127	16,757	14,253
Other comprehensive income (loss), net of tax									652	736	(198)
Comprehensive income									$ 13,779	$ 17,493	$ 14,055