Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative effect, period of adoption, adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative effect, period of adoption, adjustment	Retained Earnings	Retained Earnings Cumulative effect, period of adoption, adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative effect, period of adoption, adjustment
Beginning balance (in shares) at Dec. 31, 2017			6,872,000
Beginning balance, value at Dec. 31, 2017	$ 192,802		$ 6,872	$ 61,793		$ 124,407		$ (270)	$ (191)
Beginning balance, value (Accounting Standards Update 2017-08) at Dec. 31, 2017		$ (62)					$ (62)		0
Beginning balance, value (Accounting Standards Update 2016-01) at Dec. 31, 2017		0					191		$ (191)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(7,088)					(7,088)
Stock-based compensation expense	816			816
Exercise of stock options and vesting of restricted stock units, net (in shares)			27,000
Exercise of stock options and vesting of restricted stock units, net	$ 28		$ 27	1
Repurchase of common stock (in shares)	(15,468)		(16,000)
Repurchase of common stock	$ (494)		$ (16)	(478)
Other comprehensive income (loss), net of tax	(59)							(59)
Net income	20,004					20,004
Ending balance (in shares) at Dec. 31, 2018			6,883,000
Ending balance, value at Dec. 31, 2018	205,947		$ 6,883	62,132		137,452		(520)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(8,528)					(8,528)
Stock-based compensation expense	832			832
Exercise of stock options and vesting of restricted stock units, net (in shares)			24,000
Exercise of stock options and vesting of restricted stock units, net	$ (207)		$ 24	(231)
Repurchase of common stock (in shares)	(347,676)		(348,000)
Repurchase of common stock	$ (12,569)		$ (348)	(12,221)
Other comprehensive income (loss), net of tax	$ 951							951
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201609Member
Net income	$ 20,691					20,691
Ending balance (in shares) at Dec. 31, 2019	6,558,809		6,559,000
Ending balance, value at Dec. 31, 2019	$ 207,117	$ 0	$ 6,559	50,512	$ 139	149,615	$ (139)	431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividend declared	(8,866)					(8,866)
Stock-based compensation expense	943			943
Exercise of stock options and vesting of restricted stock units, net (in shares)			19,000
Exercise of stock options and vesting of restricted stock units, net	$ (118)		$ 19	(137)
Repurchase of common stock (in shares)	(327,000)		(327,000)
Repurchase of common stock	$ (9,976)		$ (327)	(9,649)
Other comprehensive income (loss), net of tax	(413)							(413)
Net income	$ 32,888					32,888
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