Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2012	$ 235,054		$ 6,924	$ 22,398	$ 236,065	$ (30,333)
Balance (in shares) at Dec. 31, 2012		18,464,450
Increase (Decrease) in Stockholders' Equity
Net Earnings	40,231		0	0	40,231	0
Other Comprehensive Income (Loss)	5,362		0	0	0	5,362
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares)	6,722		173	6,549	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares) (in shares)		461,192
Share-Based Compensation	6,689		0	6,689	0	0
Dividends paid ($0.72, $0.78 and $0.80) per Common Share)	(13,233)		0	0	(13,233)	0
Tax Benefit on Stock Plans	5,178		0	5,178	0	0
Purchases of Common Stock	(22,157)		(163)	(8,858)	(13,136)	0
Purchases of Common Stock (in shares)		(434,118)
Balance at Dec. 31, 2013	263,846		6,934	31,956	249,927	(24,971)
Balance (in shares) at Dec. 31, 2013		18,491,524
Increase (Decrease) in Stockholders' Equity
Net Earnings	50,651		0	0	50,651	0
Other Comprehensive Income (Loss)	(13,622)		0	0	0	(13,622)
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares)	(748)		56	(804)	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares) (in shares)		148,557
Share-Based Compensation	7,314		0	7,314	0	0
Dividends paid ($0.72, $0.78 and $0.80) per Common Share)	(14,487)		0	0	(14,487)	0
Tax Benefit on Stock Plans	1,793		0	1,793	0	0
Purchases of Common Stock	(14,096)		(84)	(14,012)	0	0
Purchases of Common Stock (in shares)		(225,034)
Balance at Dec. 31, 2014	$ 280,651		6,906	26,247	286,091	(38,593)
Balance (in shares) at Dec. 31, 2014	18,415,047	18,415,047
Increase (Decrease) in Stockholders' Equity
Net Earnings	$ 32,088		0	0	32,088	0
Other Comprehensive Income (Loss)	(9,536)		0	0	0	(9,536)
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares)	419		35	384	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (9,457, 46,152 and 23,160 shares) (in shares)		93,380
Share-Based Compensation	8,222		0	8,222	0	0
Dividends paid ($0.72, $0.78 and $0.80) per Common Share)	(14,498)		0	0	(14,498)	0
Tax Benefit on Stock Plans	859		0	859	0	0
Purchases of Common Stock	(45,998)		(287)	(35,712)	(9,999)	0
Purchases of Common Stock (in shares)		(764,046)
Balance at Dec. 31, 2015	$ 252,207		$ 6,654	$ 0	$ 293,682	$ (48,129)
Balance (in shares) at Dec. 31, 2015	17,744,381	17,744,381