Consolidated Statements of Stockholders' Equity - USD ($)		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, 2012		$ 256,598,000	$ 4,671,000	$ 150,750,000	$ 106,239,000	$ (5,062,000)	$ 982,000	$ (982,000)
Beginning Balances, shares at Dec. 31, 2012			14,396,248
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		32,787,000			32,787,000
Other comprehensive loss		2,529,000				2,529,000
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(14,758,000)	$ 0	(6,000)	(14,752,000)		0
Conversion of Debentures		295,000	$ 8,000	287,000
Conversion of debentures, shares			26,075
Share-based compensation		1,322,000	$ 12,000	1,310,000
Share-based compensation, shares	[1],[2]		35,022
Treasury stock activities		0	$ 0				142,000	(142,000)
Ending Balances at Dec. 31, 2013		278,773,000	$ 4,691,000	152,341,000	124,274,000	(2,533,000)	1,124,000	(1,124,000)
Ending Balances, shares at Dec. 31, 2013			14,457,345
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		36,092,000			36,092,000
Other comprehensive loss		(3,143,000)				(3,143,000)
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(15,675,000)		0	(15,675,000)
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		1,860,000	$ 16,000	1,844,000
Conversion of Debentures		535,000	$ 15,000	520,000
Conversion of debentures, shares			47,313
Share-based compensation		1,889,000	$ 13,000	1,876,000
Share-based compensation, shares	[1],[2]		40,686
Stock Split in Form of Stock Dividend Adjustment to Retained Earnings		(9,000)	$ 2,365,000		(2,374,000)
Treasury stock activities		0					134,000	(134,000)
Ending Balances at Dec. 31, 2014		300,322,000	$ 7,100,000	156,581,000	142,317,000	(5,676,000)	1,258,000	(1,258,000)
Ending Balances, shares at Dec. 31, 2014			14,588,711
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		41,140,000			41,140,000
Other comprehensive loss		(164,000)				(164,000)
Stock Issued During Period, Value, Dividend Reinvestment Plan		2,235,000
Stock Issued During Period, Shares, Acquisitions			592,970
Stock Issued During Period, Value, Acquisitions		30,165,000	$ 289,000	29,876,000
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(17,222,000)			(17,222,000)
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			43,275
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan			$ 21,000	2,214,000
Conversion of Debentures		0	$ 22,000	1,640,000
Conversion of debentures, shares	[1],[2]		45,703
Share-based compensation		1,662,000
Treasury stock activities		0					625,000	(625,000)
Ending Balances at Dec. 31, 2015		$ 358,138,000	$ 7,432,000	$ 190,311,000	$ 166,235,000	$ (5,840,000)	$ 1,883,000	$ (1,883,000)
Ending Balances, shares at Dec. 31, 2015			15,270,659

[1] Includes amounts for shares issued for directors’ compensation.

[2] The shares issued under the SICP are net of shares withheld for employee taxes. For 2015, 2014 and 2013, we withheld 12,620, 12,687 and 15,617 shares, respectively, for taxes.