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]
Beginning Balances at Dec. 31, 2016		$ 446,086	[1]	$ 7,935	$ 250,967		$ 192,062	$ (4,878)	$ 2,416	$ (2,416)
Beginning Balances, shares at Dec. 31, 2016	[1],[2]			16,303,499
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		58,124					58,124
Other comprehensive loss		606						606
Dividends		(21,045)					21,045
Proceeds from issuance of common stock, net of expenses		(10)	[3]	$ 0	(10)
Stock Issued During Period, Shares, New Issues				0
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan		735		$ 5	730
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan				10,771
Share-based compensation		1,798	[4],[5]	$ 15	1,783
Share-based compensation, shares				30,172
Treasury stock activities		0							979	(979)
Ending Balances at Dec. 31, 2017		486,294	[1]	$ 7,955	253,470		229,141	(4,272)	3,395	(3,395)
Ending Balances, shares at Dec. 31, 2017	[1],[2]			16,344,442
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		56,580					56,580
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(1,498)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect							907	(907)
Other comprehensive loss		(1,534)						(1,534)
Dividends		(23,600)					23,600
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0
Stock Issued During Period, Value, Dividend Reinvestment Plan		(3)		$ 0	(3)
Proceeds from issuance of common stock, net of expenses		0
Share-based compensation		2,200	[4],[5]	$ 16	2,184	[4],[5]
Share-based compensation, shares	[4],[5]			34,103
Treasury stock activities									459	(459)
Ending Balances at Dec. 31, 2018		518,439		$ 7,971	255,651		261,530	(6,713)	3,854	(3,854)
Ending Balances, shares at Dec. 31, 2018	[1],[2]			16,378,545
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		65,153
Prior Period Reclassification Adjustment							115	(115)
Other comprehensive loss		561						561
Dividends		(26,191)					26,191
Stock Issued During Period, Value, Dividend Reinvestment Plan		(3)			(3)
Proceeds from issuance of common stock, net of expenses		0
Share-based compensation		3,618	[4],[5]	$ 13	3,605	[4],[5]
Share-based compensation, shares	[4],[5]			25,231
Treasury stock activities									689	(689)
Ending Balances at Dec. 31, 2019		$ 561,577		$ 7,984	$ 259,253		$ 300,607	$ (6,267)	$ 4,543	$ (4,543)
Ending Balances, shares at Dec. 31, 2019	[1],[2]			16,403,776

[1] Includes 95,329, 97,053 and 90,961 shares at December 31, 2019, 2018 and 2017, 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 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.

[3] Represents capitalized legal fees associated with our September 22, 2016 public offering.

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

[5] The shares issued under the SICP are net of shares withheld for employee taxes. For 2019, 2018 and 2017, we withheld 7,635, 16,918 and 10,269 shares, respectively, for taxes.