Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data	Total USD ($)	Common Shares	Common Stock USD ($)	Additional Paid-in Capital USD ($)	Retained Earnings USD ($)	Accumulated Other Comprehensive Loss USD ($)
Balance at Dec. 31, 2010	$ 216,133		$ 7,140	$ 10,876	$ 220,391	$ (22,274)
Balance (in shares) at Dec. 31, 2010		19,038,843
Net Earnings	32,713		0	0	32,713	0
Other Comprehensive (Loss) Income	(6,963)		0	0	0	(6,963)
Issue Stock for Directors, Employee Benefit and Stock Plans	4,118		99	4,019	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans (in shares)		265,401
Share-Based Compensation	4,041		0	4,041	0	0
Dividends paid ($0.68, $0.69 and $0.72 per Common Share)	(12,852)		0	0	(12,852)	0
Tax Benefit on Stock Plans	1,265		0	1,265	0	0
Purchases of Common Stock	(17,603)		(176)	(5,119)	(12,308)	0
Purchases of Common Stock (in shares)		(469,304)
Balance at Dec. 31, 2011	220,852		7,063	15,082	227,944	(29,237)
Balance (in shares) at Dec. 31, 2011		18,834,940
Net Earnings	41,584		0	0	41,584	0
Other Comprehensive (Loss) Income	(1,096)		0	0	0	(1,096)
Issue Stock for Directors, Employee Benefit and Stock Plans	2,517		94	2,423	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans (in shares)		250,850
Share-Based Compensation	7,310		0	7,310	0	0
Dividends paid ($0.68, $0.69 and $0.72 per Common Share)	(12,817)		0	0	(12,817)	0
Tax Benefit on Stock Plans	2,047		0	2,047	0	0
Purchases of Common Stock	(25,343)		(233)	(4,464)	(20,646)	0
Purchases of Common Stock (in shares)		(621,340)
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	18,464,450
Net Earnings	40,231		0	0	40,231	0
Other Comprehensive (Loss) Income	5,362		0	0	0	5,362
Issue Stock for Directors, Employee Benefit and Stock Plans	6,722		173	6,549	0	0
Issue Stock for Directors, Employee Benefit and Stock Plans (in shares)		461,192
Share-Based Compensation	6,689		0	6,689	0	0
Dividends paid ($0.68, $0.69 and $0.72 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	18,491,524