CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total
Balance at Dec. 31, 2019	$ 275	$ 190,524	$ 134,287	$ 7,832		$ 332,918
Balance (in shares) at Dec. 31, 2019	27,457,306
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			13,640			13,640
Other comprehensive income (loss)				9,379		9,379
Stock-based compensation		163				163
Cash dividends and dividend equivalents			(8,260)			(8,260)
Balance at Jun. 30, 2020	$ 275	190,687	139,667	17,211		347,840
Balance (in shares) at Jun. 30, 2020	27,457,306
Balance at Mar. 31, 2020	$ 275	190,591	136,378	12,569		339,813
Balance (in shares) at Mar. 31, 2020	27,457,306
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			7,419			7,419
Other comprehensive income (loss)				4,642		4,642
Stock-based compensation		96				96
Cash dividends and dividend equivalents			(4,130)			(4,130)
Balance at Jun. 30, 2020	$ 275	190,687	139,667	17,211		347,840
Balance (in shares) at Jun. 30, 2020	27,457,306
Balance at Dec. 31, 2020	$ 275	190,875	154,614	18,153		363,917
Balance (in shares) at Dec. 31, 2020	27,457,306
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			28,962			28,962
Other comprehensive income (loss)				(9,767)		(9,767)
Stock-based compensation		310				310
Issuance of common stock upon vesting of restricted stock units (in shares)	20,225
Repurchase of common stock					$ (1,980)	(1,980)
Repurchase of common stock (in shares)	(122,478)
Cash dividends and dividend equivalents			(8,248)			(8,248)
Balance at Jun. 30, 2021	$ 275	191,185	175,328	8,386	(1,980)	373,194
Balance (in shares) at Jun. 30, 2021	27,355,053
Balance at Mar. 31, 2021	$ 275	191,004	165,735	1,906	(1,514)	357,406
Balance (in shares) at Mar. 31, 2021	27,382,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			13,717			13,717
Other comprehensive income (loss)				6,480		6,480
Stock-based compensation		181				181
Repurchase of common stock					(466)	(466)
Repurchase of common stock (in shares)	(27,016)
Cash dividends and dividend equivalents			(4,124)			(4,124)
Balance at Jun. 30, 2021	$ 275	$ 191,185	$ 175,328	$ 8,386	$ (1,980)	$ 373,194
Balance (in shares) at Jun. 30, 2021	27,355,053