Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus[Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2015	$ 419,272	$ 46,249	$ 106,269	$ 390,690	$ (120,104)	$ (3,832)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Available to Common Shareholders	52,128			52,128
Other comprehensive income	(3,180)					(3,180)
Cash dividends declared	(25,801)			(25,801)
Stock-based compensation expense, net	1,979		1,979
Restricted Awards Granted	39		(1,706)		1,745
Stock issued during period, value, new issues	6,864	269	6,595
Exercise of stock options	1,155		(264)		1,419
Purchase of treasury shares	(10,018)				(10,018)
Ending balance at Dec. 31, 2016	442,438	46,518	112,873	417,017	(126,958)	(7,012)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Available to Common Shareholders	54,310			54,310
Other comprehensive income	2,367					2,367
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2018-02 [Member]	999					(999)
Cash dividends declared	(27,845)			(27,845)
Stock-based compensation expense, net	2,097		2,097
Restricted Awards Granted	0		(1,351)		1,351
Stock issued during period, value, new issues	28,408	1,101	27,307
Exercise of stock options	732		34		698
Ending balance at Dec. 31, 2017	502,507	47,619	140,960	444,481	(124,909)	(5,644)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Available to Common Shareholders	70,002			70,002
Other comprehensive income	(6,181)					(6,181)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2016-01 [Member]	2,657					(2,657)
Cash dividends declared	(31,173)			(31,173)
Stock-based compensation expense, net	2,151		2,151
Restricted Awards Granted	0		(1,585)		1,585
Exercise of stock options	1,164		(736)		1,900
Purchase of treasury shares	(20,271)				(20,271)
Stock Issued During Period, Value, Acquisitions	82,565		28,765		53,800
Ending balance at Dec. 31, 2018	$ 600,764	$ 47,619	$ 169,555	$ 485,967	$ (87,895)	$ (14,482)