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	11,702			11,702
Other comprehensive income (loss)	2,743					2,743
Cash dividends declared	(6,429)			(6,429)
Stock-based compensation expense, net	755		755		0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0		(887)		887
Purchase of treasury shares	(9,925)				(9,925)
Ending balance at Mar. 31, 2016	418,118	46,249	106,137	395,963	(129,142)	(1,089)
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	16,026			16,026
Other comprehensive income (loss)	873					873
Cash dividends declared	(6,917)			(6,917)
Stock-based compensation expense, net	780		780		0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0		(638)		638
Issuance of shares of common stock	28,408	1,101	27,307
Exercise of stock options	38		(17)		55
Ending balance at Mar. 31, 2017	$ 481,646	$ 47,619	$ 140,305	$ 426,126	$ (126,265)	$ (6,139)