Consolidated Statements Of Changes In Shareholders' Equity - 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, 2014	$ 390,853	$ 46,249	$ 107,370	$ 362,211	$ (120,818)	$ (4,159)
Net income	40,582			40,582
Other comprehensive income (loss)	599					599
Cash dividends declared	(19,242)			(19,242)
Stock-based compensation expense, net	1,430		(38)		1,468
Exercise of stock options	2,649		(459)		3,108
Exercise of 61,796 warrants	1,896		(765)		2,661
Ending balance at Sep. 30, 2015	418,767	46,249	106,108	383,551	(113,581)	(3,560)
Beginning Balance at Dec. 31, 2015	419,272	46,249	106,269	390,690	(120,104)	(3,832)
Net income	37,476			37,476
Other comprehensive income (loss)	5,086					5,086
Cash dividends declared	(19,343)			(19,343)
Stock-based compensation expense, net	1,606		(59)		1,665
Exercise of stock options	705		(214)		919
Purchase of 231,132 treasury shares	(10,018)				(10,018)
Ending balance at Sep. 30, 2016	$ 434,784	$ 46,249	$ 105,996	$ 408,823	$ (127,538)	$ 1,254