Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data		Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Deferred Compensation [Member]	Treasury Stock [Member]
Beginning Balances at Dec. 31, 2009		$ 209,781	$ 4,572	$ 144,502	$ 63,231	$ (2,524)	$ 739	$ (739)
Beginning Balances, shares at Dec. 31, 2009	[1]		9,394,314
Net Income		26,056			26,056
Other comprehensive loss		(836)				(836)
Dividend Reinvestment Plan		1,725	26	1,699
Dividend Reinvestment Plan, shares	[1]		53,806
Retirement Savings Plan		903	14	889
Retirement Savings Plan, shares	[1]		27,795
Conversion of debentures		202	6	196
Conversion of debentures, shares	[1]		11,865
Share-based compensation	[2],[3]	637	17	620
Share-based compensation, shares	[1],[2],[3]		36,415
Tax benefit on share-based compensation		253		253
Deferred Compensation Plan							38	(38)
Purchase of treasury stock		(38)						(38)
Purchase of treasury stock, shares	[1]		(1,144)
Sale and distribution of treasury stock		38						38
Sale and distribution of treasury stock, shares	[1]		1,144
Dividends on share-based compensation		(104)			(104)
Cash dividends	[4]	(12,378)			(12,378)
Ending Balances at Dec. 31, 2010		226,239	4,635	148,159	76,805	(3,360)	777	(777)
Ending Balances, shares at Dec. 31, 2010	[1]		9,524,195
Net Income		27,622			27,622
Other comprehensive loss		(1,167)				(1,167)
Dividend Reinvestment Plan		(22)		(22)
Retirement Savings Plan		80	1	79
Retirement Savings Plan, shares	[1]		2,002
Conversion of debentures		181	5	176
Conversion of debentures, shares	[1]		10,680
Share-based compensation	[2],[3]	1,013	15	998
Share-based compensation, shares	[1],[2],[3]		30,430
Tax benefit on share-based compensation		13		13
Deferred Compensation Plan							40	(40)
Purchase of treasury stock		(40)						(40)
Purchase of treasury stock, shares	[1]		(993)
Sale and distribution of treasury stock		40						40
Sale and distribution of treasury stock, shares	[1]		993
Dividends on share-based compensation		(129)			(129)
Cash dividends	[4]	(13,050)			(13,050)
Ending Balances at Dec. 31, 2011		240,780	4,656	149,403	91,248	(4,527)	817	(817)
Ending Balances, shares at Dec. 31, 2011	[1]		9,567,307
Net Income		28,863			28,863
Other comprehensive loss		(535)				(535)
Dividend Reinvestment Plan		(7)		(7)
Conversion of debentures		186	5	181
Conversion of debentures, shares	[1]		10,975
Share-based compensation	[2],[3]	1,011	10	1,001
Share-based compensation, shares	[1],[2],[3]		19,217
Tax benefit on share-based compensation		172		172
Deferred Compensation Plan							165	(165)
Purchase of treasury stock		(45)						(45)
Purchase of treasury stock, shares	[1]		(1,019)
Sale and distribution of treasury stock		45						45
Sale and distribution of treasury stock, shares	[1]		1,019
Dividends on share-based compensation		(64)			(64)
Cash dividends	[4]	(13,808)			(13,808)
Ending Balances at Dec. 31, 2012		$ 256,598	$ 4,671	$ 150,750	$ 106,239	$ (5,062)	$ 982	$ (982)
Ending Balances, shares at Dec. 31, 2012	[1]		9,597,499

[1] Includes 33,461, 30,597 and 29,596, shares at December 31, 2012, 2011 and 2010, respectively, held in a Rabbi Trust established by the Company relating to the Deferred Compensation Plan.

[2] Includes amounts for shares issued for Directors' compensation.

[3] The shares issued under the Performance Incentive Plan ("PIP") are net of shares withheld for employee taxes. For 2012, 2011 and 2010, the Company withheld 5,670, 12,234 and 17,695 shares, respectively, for taxes.

[4] Cash dividends per share for the periods ended December 31, 2012, 2011 and 2010 were $1.440, $1.365, and $1.305 respectively.