Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 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]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares Held In Trust For Deferred Compensation Plan		97,053
Common Stock, Dividends, Per Share, Declared		$ 1.18
Beginning Balances (shares) at Dec. 31, 2018	[1],[2]			16,378,545
Beginning Balances at Dec. 31, 2018		$ 518,439		$ 7,971	[1]	$ 255,651		$ 261,530	$ (6,713)	$ 3,854	$ (3,854)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		42,589						42,589
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		0						115	(115)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect									(115)
Other comprehensive income (loss)		1,425							1,425
Other Comprehensive Income (Loss), Net of Tax		1,425
Dividend declared		(19,540)						(19,540)
Retirement savings plan and dividend reinvestment plan (shares)				0
Dividend reinvestment plan		(3)		$ 0		(3)
Share-based compensation (shares)				25,231
Share-based compensation and tax benefit		1,801	[3],[4]	$ 13		1,788	[3],[4]
Treasury stock activities		0								651	(651)
Ending Balances (shares) at Sep. 30, 2019	[1],[2]			16,403,776
Ending Balances at Sep. 30, 2019		$ 544,711	[1]	$ 7,984	[1]	257,436		284,694	(5,403)	4,505	(4,505)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		7,635
Common Stock, Dividends, Per Share, Declared		$ 0.4050
Beginning Balances (shares) at Jun. 30, 2019	[1],[2]			16,403,776
Beginning Balances at Jun. 30, 2019		$ 544,384	[1]	$ 7,984	[1]	256,385		285,762	(5,747)	4,694	(4,694)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		5,621						5,621
Other comprehensive income (loss)		344							344
Other Comprehensive Income (Loss), Net of Tax		344
Dividend declared		(6,689)						(6,689)
Dividend reinvestment plan		(1)				(1)
Share-based compensation (shares)	[3],[4]			0
Share-based compensation and tax benefit		1,052	[3],[4]	$ 0	[3],[4]	1,052
Treasury stock activities										(189)	189
Ending Balances (shares) at Sep. 30, 2019	[1],[2]			16,403,776
Ending Balances at Sep. 30, 2019		$ 544,711	[1]	$ 7,984	[1]	257,436		284,694	(5,403)	4,505	(4,505)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares Held In Trust For Deferred Compensation Plan		94,923
Preferred Stock, Shares Authorized		2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Shares Held In Trust For Deferred Compensation Plan		95,329
Common Stock, Dividends, Per Share, Declared		$ 1.285
Beginning Balances (shares) at Dec. 31, 2019	[1]			16,403,776
Beginning Balances at Dec. 31, 2019		$ 561,577	[1]	$ 7,984	[1]	259,253		300,607	(6,267)	4,543	(4,543)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		49,146						49,146
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification								(30)
Other comprehensive income (loss)		2,638							2,638
Other Comprehensive Income (Loss), Net of Tax		2,638
Dividend declared		(21,366)						(21,366)
Retirement savings plan and dividend reinvestment plan (shares)				258,260
Dividend reinvestment plan		21,819		$ 126		21,693
Share-based compensation (shares)				34,456
Share-based compensation and tax benefit	[3],[4]	2,906		$ 16		2,890
Treasury stock activities		0								1,091	(1,091)
Ending Balances (shares) at Sep. 30, 2020	[1]			16,696,492
Ending Balances at Sep. 30, 2020		$ 616,690	[1]	$ 8,126	[1]	283,836		328,357	(3,629)	5,634	(5,634)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		10,319
Common Stock, Dividends, Per Share, Declared		$ 0.4400
Beginning Balances (shares) at Jun. 30, 2020	[1]			16,463,808
Beginning Balances at Jun. 30, 2020		$ 593,277	[1]	$ 8,013	[1]	263,272		326,454	(4,462)	5,659	(5,659)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		9,261						9,261
Other comprehensive income (loss)		833							833
Other Comprehensive Income (Loss), Net of Tax		833
Dividend declared		(7,358)						(7,358)
Retirement savings plan and dividend reinvestment plan (shares)				232,684
Dividend reinvestment plan		19,533		$ 113		19,420
Share-based compensation (shares)
Share-based compensation and tax benefit		1,144	[3],[4]			1,144	[3],[4]
Treasury stock activities		0								(25)	25
Ending Balances (shares) at Sep. 30, 2020	[1]			16,696,492
Ending Balances at Sep. 30, 2020		$ 616,690	[1]	$ 8,126	[1]	$ 283,836		$ 328,357	$ (3,629)	$ 5,634	$ (5,634)
Preferred Stock, Shares Authorized		2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares Held In Trust For Deferred Compensation Plan		104,119

[1] 2,000,000 shares of preferred stock at $0.01 par value have been authorized. No shares have been issued or are outstanding; accordingly, no information has been included in the statements of stockholders’ equity.

[2] Includes 104,119 shares at September 30, 2020, 95,329 shares at December 31, 2019, 94,923 shares at September 30, 2019 and 97,053 shares at December 31, 2018, respectively, held in a Rabbi Trust related to our Non-Qualified Deferred Compensation Plan.

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

[4] The shares issued under the SICP are net of shares withheld for employee taxes. For the nine months ended September 30, 2020 and 2019, we withheld 10,319 and 7,635 shares, respectively, for employee taxes.(5)Includes the Retirement Savings Plan, DRIP and ATM equity issuances.