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, 2013	$ 5,966	$ 125,062	$ 75,939	$ (10,980)	$ (5,560)	$ 190,427
Net income			24,033			24,033
Cash dividends			(9,337)			(9,337)
Issuance of common shares pursuant to stock-based compensation plan, net		(594)		(38)		(632)
Exercise of stock options and SARs		(340)		159		(181)
Stock-based compensation expense		2,041				2,041
Purchase of common shares				(1,848)		(1,848)
Other comprehensive income (loss)					(4,071)	(4,071)
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		(1,250)		797		(453)
Exercise of stock options and SARs		(687)		293		(394)
Stock-based compensation expense		2,058				2,058
Purchase of common shares				(10,591)		(10,591)
Other comprehensive income (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		(1,231)		566		(665)
Exercise of stock options and SARs		(1,364)		651		(713)
Stock-based compensation expense		1,959				1,959
Purchase of common shares				(9,215)		(9,215)
Excess tax benefits associated with stock based compensation		2,801				2,801
Other comprehensive income (loss)					(7,879)	(7,879)
Balance at Dec. 31, 2016	$ 5,966	$ 128,455	$ 118,363	$ (30,206)	$ (14,543)	$ 208,035