Consolidated Statements Of Changes In Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus[Member]	Retained Earnings [Member]	Treasury Stock [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	24,244			24,244
Other comprehensive income (loss)	5,869					5,869
Cash dividends declared	(12,890)			(12,890)
Stock-based compensation expense	1,161		1,161
Restricted Awards Granted	39		(1,578)		1,617
Exercise of stock options	682		(204)		886
Purchase of treasury shares	(10,018)				(10,018)
Ending balance at Jun. 30, 2016	428,359	46,249	105,648	402,044	(127,619)	2,037
Beginning 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	30,714			30,714
Other comprehensive income (loss)	2,927					2,927
Cash dividends declared	(13,787)			(13,787)
Stock-based compensation expense	1,210		1,210
Restricted Awards Granted	0		(1,317)		1,317
Issuance of shares of common stock	28,408	1,101	27,307
Exercise of stock options	597		(101)		698
Ending balance at Jun. 30, 2017	$ 492,507	$ 47,619	$ 139,972	$ 433,944	$ (124,943)	$ (4,085)