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]
Beginning Balances (shares) at Dec. 31, 2017	[1]			16,344,442
Beginning Balances at Dec. 31, 2017		$ 486,294	[1]	$ 7,955	$ 253,470	$ 229,141	$ (4,272)	$ 3,395	$ (3,395)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		26,855				26,855
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(1,498)				(1,498)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect		0				907	(907)
Other comprehensive income (loss)		(1,694)					(1,694)
Dividend declared		(5,381)				(5,381)
Retirement savings plan and dividend reinvestment plan (shares)				0
Dividend reinvestment plan		(1)		$ 0	(1)
Share-based compensation (shares)	[2],[3]			19,350
Share-based compensation and tax benefit	[2],[3]	666		$ 9	657
Treasury stock activities		0						178	(178)
Ending Balances (shares) at Mar. 31, 2018	[1],[4]			16,363,792
Ending Balances at Mar. 31, 2018		$ 505,241	[4]	$ 7,964	254,126	250,024	(6,873)	3,573	(3,573)
Preferred Stock, Shares Authorized		2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Beginning Balances (shares) at Dec. 31, 2018	[1]			16,378,545
Beginning Balances at Dec. 31, 2018		$ 518,439	[1]	$ 7,971	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	(115)
Other comprehensive income (loss)		3,089					3,089
Dividend declared		(6,198)				(6,198)
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0
Stock Issued During Period, Value, Dividend Reinvestment Plan		(1)		$ 0	(1)
Share-based compensation (shares)	[2],[3]			18,472
Share-based compensation and tax benefit	[2],[3]	(334)		$ 9	(343)
Treasury stock activities		0						522	(522)
Ending Balances (shares) at Mar. 31, 2019	[1],[4]			16,397,017
Ending Balances at Mar. 31, 2019		$ 543,659	[4]	$ 7,980	$ 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

[1] 2,000,000 shares of preferred stock at $0.01 par value have been authorized. None has been issued or is outstanding; accordingly, no information has been included in the statements of stockholders’ equity.

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

[3] The shares issued under the SICP are net of shares withheld for employee taxes. For the three months ended March 31, 2019 and 2018, we withheld 7,635 and 10,436 shares, respectively, for taxes.

[4] Includes 101,997 shares at March 31, 2019, 97,053 shares at December 31, 2018, 93,422 shares at March 31, 2018 and 90,961 shares at December 31, 2017, respectively, held in a Rabbi Trust related to our Non-Qualified Deferred Compensation Plan.