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		95,329
Common Stock, Dividends, Per Share, Declared		$ 0.845
Beginning Balances (shares) at Dec. 31, 2019	[1],[2]			16,403,776
Beginning Balances at Dec. 31, 2019		$ 561,577	[1],[2]	$ 7,984	[1],[2]	$ 259,253		$ 300,607	$ (6,267)	$ 4,543	$ (4,543)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		39,886						39,886
Other comprehensive income (loss)		1,805							1,805
Other Comprehensive Income (Loss), Net of Tax		1,805
Dividend declared		(14,009)						(14,009)
Retirement savings plan and dividend reinvestment plan (shares)				25,576
Dividend reinvestment plan		2,286		$ 13		2,273
Share-based compensation (shares)	[3],[4]			34,456
Share-based compensation and tax benefit		1,762		$ 16	[3],[4]	1,746	[3],[4]
Treasury stock activities		0								1,116	(1,116)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, QuantificationPrincipleEffectOfAdoptionQuantification		(30)						(30)
Ending Balances (shares) at Jun. 30, 2020	[1],[2]			16,463,808
Ending 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]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		10,319
Common Stock, Dividends, Per Share, Declared		$ 0.4400
Beginning Balances (shares) at Mar. 31, 2020	[1],[2]			16,433,105
Beginning Balances at Mar. 31, 2020		$ 584,129	[1]	$ 7,998	[1]	259,521		322,804	(6,194)	5,468	(5,468)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		10,956						10,956
Other comprehensive income (loss)		1,732							1,732
Other Comprehensive Income (Loss), Net of Tax		1,732
Dividend declared		(7,306)						(7,306)
Retirement savings plan and dividend reinvestment plan (shares)				21,833
Dividend reinvestment plan		1,932		$ 11		1,921
Share-based compensation (shares)	[3],[4]			8,870
Share-based compensation and tax benefit	[3],[4]	1,834		$ 4		1,830
Treasury stock activities										191	(191)
Ending Balances (shares) at Jun. 30, 2020	[1],[2]			16,463,808
Ending 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]
Shares Held In Trust For Deferred Compensation Plan		107,141
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		105,087
Common Stock, Dividends, Per Share, Declared		$ 0.92
Beginning Balances (shares) at Dec. 31, 2020	[1],[2]			17,461,841
Beginning Balances at Dec. 31, 2020		$ 697,085		$ 8,499	[1],[2]	348,482		342,969	(2,865)	5,679	(5,679)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		48,279						48,279
Other comprehensive income (loss)		3,423							3,423
Other Comprehensive Income (Loss), Net of Tax		3,423
Dividend declared		(16,312)						(16,312)
Retirement savings plan and dividend reinvestment plan (shares)				60,116
Dividend reinvestment plan		6,835		$ 29		6,806
Share-based compensation (shares)	[3],[4]			45,971
Share-based compensation and tax benefit	[3],[4]	2,254		$ 22		2,232
Treasury stock activities								0		1,524	(1,524)
Ending Balances (shares) at Jun. 30, 2021	[1],[2]			17,567,928
Ending Balances at Jun. 30, 2021		$ 741,564	[1]	$ 8,550	[1]	357,520		374,936	558	7,203	(7,203)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		14,020
Common Stock, Dividends, Per Share, Declared		$ 0.4800
Beginning Balances (shares) at Mar. 31, 2021	[1],[2]			17,521,493
Beginning Balances at Mar. 31, 2021		$ 726,388	[1]	$ 8,528	[1]	350,875		369,623	(2,638)	6,992	(6,992)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		13,813						13,813
Other comprehensive income (loss)		3,196							3,196
Other Comprehensive Income (Loss), Net of Tax		3,196
Dividend declared		(8,500)						(8,500)
Retirement savings plan and dividend reinvestment plan (shares)				39,605
Dividend reinvestment plan		4,621		$ 19		4,602
Share-based compensation (shares)	[3],[4]			6,830
Share-based compensation and tax benefit	[3],[4]	2,046		$ 3		2,043
Treasury stock activities		0								211	(211)
Ending Balances (shares) at Jun. 30, 2021	[1],[2]			17,567,928
Ending Balances at Jun. 30, 2021		$ 741,564	[1]	$ 8,550	[1]	$ 357,520		$ 374,936	$ 558	$ 7,203	$ (7,203)
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		117,193

[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 117,193, 105,087, 107,141, and 95,329 shares at June 30, 2021, December 31, 2020, June 30, 2020 and December 31, 2019, 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 six months ended June 30, 2021 and 2020, we withheld 14,020 and 10,319 shares, respectively, for employee taxes.