Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2009	$ 184,279	$ 7,032	$ 7,772	$ 192,584	$ (23,109)
Balance (in shares) at Dec. 31, 2009		18,750,828
Net Earnings	34,803	0	0	34,803	0
Other Comprehensive Income (Loss)	835	0	0	0	835
Issue Stock for Directors, Employee Benefit and Stock Plans	6,175	146	6,029	0	0
Issues Stock for Directors, Employee Benefit and Stock Plans (in shares)		388,015
Share-Based Compensation	2,651	0	2,651	0	0
Dividends paid	(11,181)	0	0	(11,181)	0
Tax Benefit on Stock Plans	1,724	0	1,724	0	0
Purchases of Common Stock	(3,153)	(38)	(7,300)	4,185	0
Purchases of Common Stock (in shares)		(100,000)
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 Income (Loss)	(6,963)	0	0	0	(6,963)
Issue Stock for Directors, Employee Benefit and Stock Plans	4,118	99	4,019	0	0
Issues Stock for Directors, Employee Benefit and Stock Plans (in shares)		265,401
Share-Based Compensation	4,041	0	4,041	0	0
Dividends paid	(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	18,834,940
Net Earnings	41,584	0	0	41,584	0
Other Comprehensive Income (Loss)	(1,096)	0	0	0	(1,096)
Issue Stock for Directors, Employee Benefit and Stock Plans	2,517	94	2,423	0	0
Issues Stock for Directors, Employee Benefit and Stock Plans (in shares)		250,850
Share-Based Compensation	7,310	0	7,310	0	0
Dividends paid	(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