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			24,033			24,033
Cash dividends			(11,317)			(11,317)
Issuance of common shares pursuant to stock-based compensation plan, net		(1,426)		1,324		(102)
Exercise of SARs		(855)		464		(391)
Stock-based compensation expense		2,286				2,286
Purchase of common shares				(7,799)		(7,799)
Other comprehensive income					10,059	10,059
Balance at Sep. 30, 2019	7,753	205,775	87,887	(45,985)	(8,813)	246,617
Balance at Jun. 30, 2019	7,753	205,463	83,470	(46,333)	(9,932)	240,421
Net income			8,186			8,186
Cash dividends			(3,769)			(3,769)
Issuance of common shares pursuant to stock-based compensation plan, net		(5)		48		43
Exercise of SARs		(552)		300		(252)
Stock-based compensation expense		869				869
Other comprehensive income					1,119	1,119
Balance at Sep. 30, 2019	7,753	205,775	87,887	(45,985)	(8,813)	246,617
Balance at Dec. 31, 2019	7,753	205,397	90,341	(45,381)	(13,920)	244,190
Net income			18,765			18,765
Cash dividends			(11,704)			(11,704)
Issuance of common shares pursuant to stock-based compensation plan, net		(2,378)		1,338		(1,040)
Exercise of SARs		(243)		141		(102)
Stock-based compensation expense		2,277				2,277
Purchase of common shares				(5,508)		(5,508)
Other comprehensive income					4,613	4,613
Balance at Sep. 30, 2020	7,753	205,053	97,402	(49,410)	(9,307)	251,491
Balance at Jun. 30, 2020	7,753	204,258	95,514	(49,457)	(9,541)	248,527
Net income			5,781			5,781
Cash dividends			(3,893)			(3,893)
Issuance of common shares pursuant to stock-based compensation plan, net		(4)		47		43
Stock-based compensation expense		799				799
Other comprehensive income					234	234
Balance at Sep. 30, 2020	$ 7,753	$ 205,053	$ 97,402	$ (49,410)	$ (9,307)	$ 251,491