CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands		Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2014		$ 5,966	$ 126,169	$ 90,635	$ (12,707)	$ (9,631)	$ 200,432
Net income				23,056			23,056
Cash dividends				(9,697)			(9,697)
Issuance of common shares pursuant to stock-based compensation plan, net	[1]		(1,250)		797		(453)
Exercise of SARs			(687)		293		(394)
Stock-based compensation expense			2,058				2,058
Purchase of common shares	[1]				(10,591)		(10,591)
Other comprehensive loss						2,967	2,967
Balance at Dec. 31, 2015		5,966	126,290	103,994	(22,208)	(6,664)	207,378
Net income				24,348			24,348
Cash dividends				(9,979)			(9,979)
Issuance of common shares pursuant to stock-based compensation plan, net	[1]		(1,231)		566		(665)
Exercise of SARs			(1,364)		651		(713)
Stock-based compensation expense			1,959				1,959
Purchase of common shares	[1]				(9,215)		(9,215)
Excess tax benefits associated with stock based compensation			2,801				2,801
Other comprehensive loss						(7,879)	(7,879)
Balance at Dec. 31, 2016		5,966	128,455	118,363	(30,206)	(14,543)	208,035
Net income				25,014			25,014
Cash dividends				(10,675)			(10,675)
Stock dividend		558	75,108	(75,674)			(8)
Issuance of common shares pursuant to stock-based compensation plan, net	[1]		(821)		273		(548)
Exercise of SARs			(451)		142		(309)
Stock-based compensation expense			2,340				2,340
Purchase of common shares	[1]				(2,270)		(2,270)
Other comprehensive loss						3,509	3,509
Other comprehensive income
reclassification for ASU 2018-02				2,286		(2,286)
Balance at Dec. 31, 2017		$ 6,524	$ 204,631	$ 59,314	$ (32,061)	$ (13,320)	$ 225,088

[1] (1) Share and per share figures adjusted for the 10% stock dividend that occurred on December 15, 2017