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		$ 0.4050
Beginning Balances (shares) at Dec. 31, 2019	[1],[2]			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		28,930					28,930
Other comprehensive income (loss)		73						73
Other Comprehensive Income (Loss), Net of Tax		73
Dividend declared		(6,703)					(6,703)
Retirement savings plan and dividend reinvestment plan (shares)				3,743
Dividend reinvestment plan		354		$ 2		352
Share-based compensation (shares)	[3],[4]			25,586
Share-based compensation and tax benefit	[3],[4]	(72)		$ 12		(84)
Treasury stock activities									925	(925)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, QuantificationPrincipleEffectOfAdoptionQuantification		(30)					(30)
Ending Balances (shares) at Mar. 31, 2020	[1],[2]			16,433,105
Ending 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]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		10,319
Shares Held In Trust For Deferred Compensation Plan		104,871
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		$ 0.44
Beginning Balances (shares) at Dec. 31, 2020	[1],[2]			17,461,841
Beginning Balances at Dec. 31, 2020		$ 697,085	[1]	$ 8,499	[1]	348,482	342,969	(2,865)	5,679	(5,679)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		34,466					34,466
Other comprehensive income (loss)		227						227
Other Comprehensive Income (Loss), Net of Tax		227
Dividend declared		(7,812)					(7,812)
Retirement savings plan and dividend reinvestment plan (shares)				20,511
Dividend reinvestment plan		2,214		$ 10		2,204
Share-based compensation (shares)	[3],[4]			39,141
Share-based compensation and tax benefit	[3],[4]	208		$ 19		189
Treasury stock activities		0							1,313	(1,313)
Ending Balances (shares) at Mar. 31, 2021	[1],[2]			17,521,493
Ending 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]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		14,020
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		116,751

[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 116,751, 105,087, 104,871, and 95,329 shares at March 31, 2021, December 31, 2020, March 31, 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 three months ended March 31, 2021 and 2020, we withheld 14,020 and 10,319 shares, respectively, for employee taxes.