Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		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, shares at Dec. 31, 2013	[1]		14,457,345
Beginning Balances at Dec. 31, 2013		$ 278,773	$ 4,691	$ 152,341	$ 124,274	$ (2,533)	$ 1,124	$ (1,124)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		36,092			36,092
Other comprehensive loss		(3,143)				(3,143)
Common Stock Dividends, Shares			0
Dividends		(15,675)			(15,675)
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			43,367
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		1,860	$ 16	1,844
Conversion of debentures, shares	[1]		47,313
Stock Issued During Period, Value, Conversion of Convertible Securities		535	$ 15	520
Share-based compensation, shares	[1],[2],[3]		40,686
Share-based compensation and tax benefit	[2],[3]	1,889	$ 13	1,876
Stock Split in Form of Stock Dividend Adjustment to Retained Earnings		(9)	$ 2,365		(2,374)
Treasury stock activities		0					134	(134)
Ending Balances, shares at Dec. 31, 2014	[1]		14,588,711
Ending Balances at Dec. 31, 2014		300,322	$ 7,100	156,581	142,317	(5,676)	1,258	(1,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		32,521			32,521
Other comprehensive loss		205				205
Common Stock Dividends, Shares			0
Dividends		(12,802)			(12,802)
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			36,289
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan			$ 18	1,849
Stock Issued During Period, Value, Dividend Reinvestment Plan		1,867
Stock Issued During Period, Shares, Acquisitions			592,970
Stock Issued During Period, Value, Acquisitions		30,165	$ 289	29,876
Share-based compensation, shares	[1],[2],[3]		45,703
Share-based compensation and tax benefit	[2],[3]	1,037	$ 22	1,015
Treasury stock activities		0					605	(605)
Ending Balances, shares at Sep. 30, 2015	[1]		15,263,673
Ending Balances at Sep. 30, 2015		$ 353,315	$ 7,429	$ 189,321	$ 162,036	$ (5,471)	$ 1,863	$ (1,863)

[1] Includes 70,253 and 57,382 shares at September 30, 2015 and December 31, 2014, respectively, held in a Rabbi Trust related to our Deferred Compensation Plan.

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

[3] The shares issued under the SICP are net of shares withheld for employee taxes. For the nine months ended September 30, 2015, and for the year ended December 31, 2014, we withheld 12,620 and 12,687 shares, respectively, for taxes.