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, 2017	$ 502,507	$ 47,619	$ 140,960	$ 444,481	$ (124,909)	$ (5,644)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	70,002			70,002
Other comprehensive income	(6,181)					(6,181)
New Accounting Pronouncement, Effect of Adoption, Quantification | Accounting Standards Update 2016-01 [Member]	0			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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	89,352			89,352
Other comprehensive income	20,322					20,322
Cash dividends declared	(36,066)			(36,066)
Stock-based compensation expense, net	2,516		2,516
Restricted Awards Granted	0		(1,657)		1,657
Exercise of stock options	526		(105)		631
Purchase of treasury shares	(19,431)				(19,431)
Ending balance at Dec. 31, 2019	657,983	47,619	170,309	539,253	(105,038)	5,840
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	89,595			89,595
Other comprehensive income	25,393					25,393
Cash dividends declared	(36,525)			(36,525)
Stock-based compensation expense, net	3,253		3,253
Restricted Awards Granted	0		(2,146)		2,146
Exercise of stock options	223		(112)		335
Purchase of treasury shares	(36,481)				(36,481)
Ending balance at Dec. 31, 2020	$ 701,106	$ 47,619	$ 171,304	$ 589,988	$ (139,038)	$ 31,233