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 at Dec. 31, 2013		$ 278,773	$ 4,691	$ 152,341	$ 124,274	$ (2,533)	$ 1,124	$ (1,124)
Beginning Balances, shares at Dec. 31, 2013			14,457,345
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		36,092			36,092
Other comprehensive loss		(3,143)				(3,143)
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(15,675)		0	(15,675)
Proceeds from issuance of common stock, net of expenses		0
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		1,860	$ 16	1,844
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			43,367
Conversion of Debentures		535	$ 15	520
Conversion of debentures, shares			47,313
Share-based compensation		1,889	$ 13	1,876
Share-based compensation, shares	[1],[2]		40,686
Stock Split in Form of Stock Dividend Adjustment to Retained Earnings		(9)	$ 2,365		(2,374)
Treasury stock activities		0					134	(134)
Ending Balances at Dec. 31, 2014		300,322	$ 7,100	156,581	142,317	(5,676)	1,258	(1,258)
Ending Balances, shares at Dec. 31, 2014			14,588,711
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		41,140			41,140
Other comprehensive loss		(164)				(164)
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(17,222)			(17,222)
Stock Issued During Period, Value, Acquisitions		30,165	$ 289	29,876
Stock Issued During Period, Shares, Acquisitions			592,970
Proceeds from issuance of common stock, net of expenses		0
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		2,235	$ 21	2,214
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			43,275
Conversion of Debentures		0	$ 22	1,640
Conversion of debentures, shares	[1],[2]		45,703
Share-based compensation		1,662
Treasury stock activities		0					625	(625)
Ending Balances at Dec. 31, 2015		358,138	$ 7,432	190,311	166,235	(5,840)	1,883	(1,883)
Ending Balances, shares at Dec. 31, 2015			15,270,659
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		44,675			44,675
Other comprehensive loss		962				962
Dividends ShareBased Compensation Dividends And Dividends For Reinvestment Plan		(18,848)			(18,848)
Proceeds from issuance of common stock, net of expenses		$ 57,360	$ 467	56,893
Stock Issued During Period, Shares, New Issues		960,488	960,488
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		$ 2,242	$ 17	2,225
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan			36,253
Conversion of Debentures		0	$ 19	1,538
Conversion of debentures, shares	[1],[2]		36,099
Share-based compensation		1,557
Treasury stock activities							533	(533)
Ending Balances at Dec. 31, 2016		$ 446,086	$ 7,935	$ 250,967	$ 192,062	$ (4,878)	$ 2,416	$ (2,416)
Ending Balances, shares at Dec. 31, 2016			16,303,499

[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 2016, 2015 and 2014, we withheld 12,031, 12,620 and 12,687 shares, respectively, for taxes