CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Total
Balance at Dec. 31, 2019	$ 7,753	$ 205,397	$ 90,341	$ (45,381)	$ (13,920)	$ 244,190
Net income			12,984			12,984
Cash dividends			(7,811)			(7,811)
Issuance of common shares pursuant to stock-based compensation plan, net		(2,374)		1,291		(1,083)
Exercise of SARs		(243)		141		(102)
Stock-based compensation expense		1,478				1,478
Purchase of common shares				(5,508)		(5,508)
Other comprehensive income					4,379	4,379
Balance at Jun. 30, 2020	7,753	204,258	95,514	(49,457)	(9,541)	248,527
Balance at Mar. 31, 2020	7,753	203,801	93,968	(49,800)	(14,439)	241,283
Net income			5,439			5,439
Cash dividends			(3,893)			(3,893)
Issuance of common shares pursuant to stock-based compensation plan, net		(299)		343		44
Stock-based compensation expense		756				756
Other comprehensive income					4,898	4,898
Balance at Jun. 30, 2020	7,753	204,258	95,514	(49,457)	(9,541)	248,527
Balance at Dec. 31, 2020	7,753	204,875	99,062	(50,515)	(15)	261,160
Net income			14,097			14,097
Cash dividends			(7,761)			(7,761)
Issuance of common shares pursuant to stock-based compensation plan, net		(2,881)		2,046		(835)
Exercise of SARs		(415)		292		(123)
Stock-based compensation expense		1,519				1,519
Purchase of common shares				(5,260)		(5,260)
Other comprehensive income					(2,030)	(2,030)
Balance at Jun. 30, 2021	7,753	203,098	105,398	(53,437)	(2,045)	260,767
Balance at Mar. 31, 2021	7,753	202,828	102,247	(49,949)	(3,392)	259,487
Net income			7,026			7,026
Cash dividends			(3,875)			(3,875)
Issuance of common shares pursuant to stock-based compensation plan, net		(455)		450		(5)
Exercise of SARs		(101)		94		(7)
Stock-based compensation expense		826				826
Purchase of common shares				(4,032)		(4,032)
Other comprehensive income					1,347	1,347
Balance at Jun. 30, 2021	$ 7,753	$ 203,098	$ 105,398	$ (53,437)	$ (2,045)	$ 260,767