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]
Shares, Issued	[1],[2]			16,344,442
Stockholders' Equity Attributable to Parent		$ 486,294	[2]	$ 7,955	$ 253,470		$ 229,141	$ (4,272)	$ 3,395	$ (3,395)
Net Income		56,580					56,580
Other comprehensive loss		(1,534)						(1,534)
Dividends		(23,600)					(23,600)
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan				0
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		(3)		$ 0	(3)
Share-based compensation, shares				34,103
Share-based compensation		2,200	[3],[4]	$ 16	2,184
Treasury stock activities		0							459	(459)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect							907	(907)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, QuantificationPrincipleEffectOfAdoptionQuantification		(1,498)					(1,498)
Shares, Issued	[1],[2]			16,378,545
Stockholders' Equity Attributable to Parent		518,439	[2]	$ 7,971	255,651		261,530	(6,713)	3,854	(3,854)
Net Income		65,153					65,153
Other comprehensive loss		561						561
Dividends		(26,191)					(26,191)
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		(3)			(3)
Share-based compensation, shares	[3],[4]			25,231
Share-based compensation		3,618	[3],[4]	$ 13	3,605	[3],[4]
Treasury stock activities									689	(689)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect		(115)					115	(115)
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0
Stock Issued During Period, Value, Dividend Reinvestment Plan				$ 0
Shares, Issued	[1],[2]			16,403,776
Stockholders' Equity Attributable to Parent		561,577		$ 7,984	259,253		300,607	(6,267)	4,543	(4,543)
Net Income		71,498
Other comprehensive loss		3,402						3,402
Dividends		(29,106)					(29,106)
Stock Issued, Value, During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan		85,851		$ 498	85,353
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan				1,023,609
Share-based compensation, shares	[3],[4]			34,456
Share-based compensation		3,893	[3],[4]	$ 17	3,876
Treasury stock activities									1,136	(1,136)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, QuantificationPrincipleEffectOfAdoptionQuantification		(30)					(30)
Shares, Issued	[1],[2]			17,461,841
Stockholders' Equity Attributable to Parent		$ 697,085		$ 8,499	$ 348,482		$ 342,969	$ (2,865)	$ 5,679	$ (5,679)

[1] 2,000,000 shares of preferred stock at $0.01 par value per share have been authorized. No shares have been issued or are outstanding; accordingly, no information has been included in the Consolidated Statements of Stockholders’ Equity.

[2] Includes 105,087, 95,329 and 97,053 shares at December 31, 2020, 2019 and 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 2020, 2019 and 2018, we withheld 10,319, 7,635 and 16,918 shares, respectively, for taxes.(5) Includes the Retirement Savings Plan, DRIP and ATM equity issuances.