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, 2018	$ 7,753	$ 205,770	$ 75,171	$ (39,974)	$ (18,872)	$ 229,848
Net income			15,847			15,847
Cash dividends			(7,548)			(7,548)
Issuance of common shares pursuant to stock-based compensation plan, net		(1,421)		1,276		(145)
Exercise of SARs		(303)		164		(139)
Stock-based compensation expense		1,417				1,417
Purchase of common shares				(7,799)		(7,799)
Other comprehensive income					8,940	8,940
Balance at Jun. 30, 2019	7,753	205,463	83,470	(46,333)	(9,932)	240,421
Balance at Mar. 31, 2019	7,753	205,310	79,558	(44,685)	(13,456)	234,480
Net income			7,684			7,684
Cash dividends			(3,772)			(3,772)
Issuance of common shares pursuant to stock-based compensation plan, net		(407)		450		43
Stock-based compensation expense		560				560
Purchase of common shares				(2,098)		(2,098)
Other comprehensive income					3,524	3,524
Balance at Jun. 30, 2019	7,753	205,463	83,470	(46,333)	(9,932)	240,421
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