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, 2017	$ 6,524	$ 204,631	$ 59,314	$ (32,061)	$ (13,320)	$ 225,088
Net income			15,601			15,601
Cash dividends			(6,144)			(6,144)
Issuance of common shares pursuant to stock-based compensation plan, net		(998)		551		(447)
Exercise of SARs		(423)		150		(273)
Stock-based compensation expense		1,477				1,477
Purchase of common shares				(883)		(883)
Other comprehensive income (loss)					(7,806)	(7,806)
Balance at Jun. 30, 2018	6,524	204,687	68,771	(32,243)	(21,126)	226,613
Balance at Mar. 31, 2018	6,524	204,479	64,458	(32,301)	(20,738)	222,422
Net income			7,509			7,509
Cash dividends			(3,196)			(3,196)
Issuance of common shares pursuant to stock-based compensation plan, net		(277)		294		17
Exercise of SARs		(354)		118		(236)
Stock-based compensation expense		839				839
Purchase of common shares				(354)		(354)
Other comprehensive income (loss)					(388)	(388)
Balance at Jun. 30, 2018	6,524	204,687	68,771	(32,243)	(21,126)	226,613
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 (loss)					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
Exercise of SARs
Stock-based compensation expense		560				560
Purchase of common shares				(2,098)		(2,098)
Other comprehensive income (loss)					3,524	3,524
Balance at Jun. 30, 2019	$ 7,753	$ 205,463	$ 83,470	$ (46,333)	$ (9,932)	$ 240,421