Condensed Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified		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, 2011		$ 240,780	$ 4,656	$ 149,403	$ 91,248	$ (4,527)	$ 817	$ (817)
Beginning Balances, shares at Dec. 31, 2011	[1]		9,567,307
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		28,863			28,863
Other comprehensive loss/income		(535)				(535)
Dividend Reinvestment Plan		(7)	0	(7)
Dividend Reinvestment Plan, shares			0
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		0					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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		23,104			23,104
Other comprehensive loss/income		159				159
Dividend Reinvestment Plan		(5)	0	(5)
Dividend Reinvestment Plan, shares	[1]		0
Conversion of debentures		88	3	85
Conversion of debentures, shares	[1]		5,166
Share-based compensation	[2],[3]	857	11	846
Share-based compensation, shares	[1],[2],[3]		23,348
Deferred Compensation Plan		0					128	(128)
Deferred Compensation Plan, shares			0
Purchase of treasury stock		(38)						(38)
Purchase of treasury stock, shares	[1]		(763)
Sale and distribution of treasury stock		38						38
Sale and distribution of treasury stock, shares	[1]			763
Dividends on share-based compensation		(92)			(92)
Cash dividends	[4]	(10,921)			(10,921)
Ending Balances at Sep. 30, 2013		$ 269,788	$ 4,685	$ 151,676	$ 118,330	$ (4,903)	$ 1,110	$ (1,110)
Ending Balances, shares at Sep. 30, 2013	[1]		9,626,013

[1] Includes 34,224 and 33,461 shares at September 30, 2013 and December 31, 2012, respectively, held in a Rabbi Trust related to the Company's 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 the nine months ended September 30, 2013 and for the year ended December 31, 2012, the Company withheld 10,411 and 5,670 shares, respectively, for taxes.

[4] Cash dividends per share for the periods ended September 30, 2013 and December 31, 2012 were $1.135 and $1.440, respectively.