Consolidated Statements of Changes In Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss), net of Tax	Cumulative effect of adoption of accounting principles	Cumulative effect of adoption of accounting principles Additional Paid-in Capital	Cumulative effect of adoption of accounting principles  Retained Earnings
Beginning balance (in shares) at Dec. 31, 2019		6,559,000
Beginning balance, value at Dec. 31, 2019	$ 207,117	$ 6,559	$ 50,512	$ 149,615	$ 431	$ 0	$ 139	$ (139)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,223)			(2,223)
Stock-based compensation expense	242		242
Repurchase of common stock (in shares)		(193,000)
Repurchase of common stock	(6,310)	$ (193)	(6,117)
Other comprehensive income (loss), net of tax	(2,136)				(2,136)
Net income	1,033			1,033
Ending balance (in shares) at Mar. 31, 2020		6,366,000
Ending balance, value at Mar. 31, 2020	197,723	$ 6,366	44,776	148,286	(1,705)
Beginning balance (in shares) at Dec. 31, 2019		6,559,000
Beginning balance, value at Dec. 31, 2019	207,117	$ 6,559	50,512	149,615	431	0	139	(139)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss), net of tax	(666)
Net income	22,788
Ending balance (in shares) at Sep. 30, 2020		6,279,000
Ending balance, value at Sep. 30, 2020	214,616	$ 6,279	42,966	165,606	(235)
Beginning balance (in shares) at Dec. 31, 2019		6,559,000
Beginning balance, value at Dec. 31, 2019	$ 207,117	$ 6,559	50,512	149,615	431	0	$ 139	(139)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-13 [Member]
Ending balance (in shares) at Dec. 31, 2020	6,251,004	6,251,000
Ending balance, value at Dec. 31, 2020	$ 221,575	$ 6,251	41,808	173,498	18	2,400		2,400
Beginning balance (in shares) at Mar. 31, 2020		6,366,000
Beginning balance, value at Mar. 31, 2020	197,723	$ 6,366	44,776	148,286	(1,705)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,188)			(2,188)
Stock-based compensation expense	238		238
Exercise of stock options and vesting of restricted stock units, net (in shares)		2,000
Exercise of stock options and vesting of restricted stock units, net	(6)	$ 2	(8)
Other comprehensive income (loss), net of tax	1,256				1,256
Net income	9,900			9,900
Ending balance (in shares) at Jun. 30, 2020		6,368,000
Ending balance, value at Jun. 30, 2020	206,923	$ 6,368	45,006	155,998	(449)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,247)			(2,247)
Stock-based compensation expense	237		237
Repurchase of common stock (in shares)		(89,000)
Repurchase of common stock	(2,366)	$ (89)	(2,277)
Other comprehensive income (loss), net of tax	214				214
Net income	11,855			11,855
Ending balance (in shares) at Sep. 30, 2020		6,279,000
Ending balance, value at Sep. 30, 2020	214,616	$ 6,279	42,966	165,606	(235)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,208)			(2,208)
Stock-based compensation expense	226		226
Exercise of stock options and vesting of restricted stock units, net (in shares)		17,000
Exercise of stock options and vesting of restricted stock units, net	(112)	$ 17	(129)
Repurchase of common stock (in shares)		(45,000)
Repurchase of common stock	(1,300)	$ (45)	(1,255)
Other comprehensive income (loss), net of tax	253				253
Net income	$ 10,100			10,100
Ending balance (in shares) at Dec. 31, 2020	6,251,004	6,251,000
Ending balance, value at Dec. 31, 2020	$ 221,575	$ 6,251	41,808	173,498	18	2,400		2,400
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,313)			(2,313)
Stock-based compensation expense	280		280
Exercise of stock options and vesting of restricted stock units, net (in shares)		17,000
Exercise of stock options and vesting of restricted stock units, net	(278)	$ 17	(295)
Repurchase of common stock (in shares)		(61,000)
Repurchase of common stock	(2,212)	$ (61)	(2,151)
Other comprehensive income (loss), net of tax	(181)				(181)
Net income	12,181			12,181
Ending balance (in shares) at Mar. 31, 2021		6,207,000
Ending balance, value at Mar. 31, 2021	$ 231,452	$ 6,207	39,642	185,766	(163)
Beginning balance (in shares) at Dec. 31, 2020	6,251,004	6,251,000
Beginning balance, value at Dec. 31, 2020	$ 221,575	$ 6,251	41,808	173,498	18	$ 2,400		$ 2,400
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss), net of tax	(934)
Net income	$ 29,403
Ending balance (in shares) at Sep. 30, 2021	6,177,300	6,177,000
Ending balance, value at Sep. 30, 2021	$ 242,474	$ 6,177	38,929	198,284	(916)
Beginning balance (in shares) at Mar. 31, 2021		6,207,000
Beginning balance, value at Mar. 31, 2021	231,452	$ 6,207	39,642	185,766	(163)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,320)			(2,320)
Stock-based compensation expense	229		229
Other comprehensive income (loss), net of tax	(488)				(488)
Net income	8,345			8,345
Ending balance (in shares) at Jun. 30, 2021		6,207,000
Ending balance, value at Jun. 30, 2021	237,218	$ 6,207	39,871	191,791	(651)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend on common stock	(2,384)			(2,384)
Stock-based compensation expense	232		232
Repurchase of common stock (in shares)		(30,000)
Repurchase of common stock	(1,204)	$ (30)	(1,174)
Other comprehensive income (loss), net of tax	(265)				(265)
Net income	$ 8,877			8,877
Ending balance (in shares) at Sep. 30, 2021	6,177,300	6,177,000
Ending balance, value at Sep. 30, 2021	$ 242,474	$ 6,177	$ 38,929	$ 198,284	$ (916)