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]
Shares issued under the performance incentive plan withheld for employee taxes (shares)		7,635
Common Stock, Dividends, Per Share, Declared		$ 0.3700
Beginning Balances (shares) at Dec. 31, 2018	[1],[2]			16,378,545
Beginning Balances at Dec. 31, 2018		$ 518,439	[2]	$ 7,971	[2]	$ 255,651	$ 261,530	$ (6,713)	$ 3,854	$ (3,854)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		28,664					28,664
Prior Period Reclassification Adjustment								(115)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		0					115
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect								(115)
Other comprehensive income (loss)		3,089						3,089
Other Comprehensive Income (Loss), Net of Tax		3,089
Dividend declared		(6,198)					(6,198)
Retirement savings plan and dividend reinvestment plan (shares)				0
Dividend reinvestment plan		(1)		$ 0		(1)
Share-based compensation (shares)	[3],[4]			18,472
Share-based compensation and tax benefit	[3],[4]	(334)		$ 9		(343)
Treasury stock activities		0							522	(522)
Ending Balances (shares) at Mar. 31, 2019	[2]			16,397,017
Ending Balances at Mar. 31, 2019		$ 543,659	[2]	$ 7,980	[2]	255,307	284,111	(3,739)	4,376	(4,376)
Preferred Stock, Shares Authorized		2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Shares issued under the performance incentive plan withheld for employee taxes (shares)		10,319
Common Stock, Dividends, Per Share, Declared		$ 0.4050
Beginning Balances (shares) at Dec. 31, 2019	[2]			16,403,776
Beginning Balances at Dec. 31, 2019		$ 561,577	[2]	$ 7,984	[2]	259,253	300,607	(6,267)	4,543	(4,543)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		28,930					28,930
Prior Period Reclassification Adjustment							(30)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(30)
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)				25,586
Share-based compensation and tax benefit	[3],[4]	(72)		$ 12		(84)
Treasury stock activities		0							925	(925)
Ending Balances (shares) at Mar. 31, 2020	[2]			16,433,105
Ending Balances at Mar. 31, 2020		$ 584,129	[2]	$ 7,998	[2]	$ 259,521	$ 322,804	$ (6,194)	$ 5,468	$ (5,468)
Preferred Stock, Shares Authorized		2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01

[1] Includes 104,871 shares at March 31, 2020, and 95,329 shares at December 31, 2019, respectively, held in a Rabbi Trust related to our Non-Qualified Deferred Compensation Plan.

[2] 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.

[3] The shares issued under the SICP are net of shares withheld for employee taxes. For the three months ended March 31, 2020 and 2019, we withheld 10,319 and 7,635 shares, respectively, for employee taxes.

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