Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Preferred Stock	Common Stock 2004 Buyback Plan [Member]	Common Stock Other Than 2004 Buyback Plan [Member]	Common Stock	Surplus 2004 Buyback Plan [Member]	Surplus Other Than 2004 Buyback Plan [Member]	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss).	2004 Buyback Plan [Member]	Other Than 2004 Buyback Plan [Member]	Total
Balance at Dec. 31, 2012				$ 42,344			$ 328,843	$ 135,986	$ 376			$ 507,549
Balance (in shares) at Dec. 31, 2012				16,937,464
Increase (Decrease) in Stockholders' Equity
Net income								49,219				49,219
Other Comprehensive Income, net of tax effects									(10,099)			(10,099)
Total comprehensive income												39,120
Cash dividends on Series A preferred stock								(1,354)				(1,354)
Cash dividends declared								(15,274)				(15,274)
Stock options exercised				$ 163			1,722					1,885
Stock options exercised (in shares)				65,555
Employee stock purchases				$ 41			740					781
Employee stock purchases (in shares)				16,907
Restricted stock awards				$ 208			(208)
Restricted stock awards (in shares)				83,110
Common stock repurchased			$ (42)			$ (891)					$ (933)
Common stock repurchased (in shares)			(17,186)
Share-based compensation expense							3,322					3,322
Common stock issued for FFHI acquisition				$ 17,546			363,827					381,373
Common stock issued for FFHI acquisition (in shares)				7,018,274
Preferred stock assumed in FFHI acquisition	$ 1						64,999					65,000
Preferred stock assumed in FFHI acquisition (in shares)	65,000
Balance at Dec. 31, 2013	$ 1			$ 60,260			762,354	168,577	(9,723)			981,469
Balance (in shares) at Dec. 31, 2013				24,104,124
Balance (in shares) Preferred Stock at Dec. 31, 2013	65,000
Increase (Decrease) in Stockholders' Equity
Net income								75,437				75,437
Other Comprehensive Income, net of tax effects									9,346			9,346
Total comprehensive income												84,783
Cash dividends on Series A preferred stock								(1,073)				(1,073)
Cash dividends declared								(19,785)				(19,785)
Stock options exercised				$ 57			652					709
Stock options exercised (in shares)				22,878
Employee stock purchases				$ 38			788					826
Employee stock purchases (in shares)				14,863
Restricted stock awards				$ 59			(59)
Restricted stock awards (in shares)				23,560
Repurchase of Series A preferred stock	$ (1)						(64,999)					(65,000)
Repurchase of Series A preferred stock (in shares)	(65,000)
Common stock repurchased			$ (37)			(880)					(917)
Common stock repurchased (in shares)			(14,723)
Share-based compensation expense							3,908					3,908
Balance at Dec. 31, 2014				$ 60,377			701,764	223,156	(377)			$ 984,920
Balance (in shares) at Dec. 31, 2014				24,150,702								24,150,702
Balance (in shares) Preferred Stock at Dec. 31, 2014												0
Increase (Decrease) in Stockholders' Equity
Net income								99,473				$ 99,473
Other Comprehensive Income, net of tax effects									(3,494)			(3,494)
Total comprehensive income												95,979
Cash dividends declared								(23,710)				(23,710)
Stock options exercised				$ 89			1,026					1,115
Stock options exercised (in shares)				35,360
Employee stock purchases				$ 34			874					908
Employee stock purchases (in shares)				13,536
Restricted stock awards				$ 110			(110)
Restricted stock awards (in shares)				44,105
Common stock repurchased		$ (150)	$ (53)		$ (4,119)	$ (1,309)				$ (4,269)	$ (1,362)
Common stock repurchased (in shares)		(60,000)	(21,046)
Share-based compensation expense							5,803					5,803
Balance at Dec. 31, 2015				$ 60,407			$ 703,929	$ 298,919	$ (3,871)			$ 1,059,384
Balance (in shares) at Dec. 31, 2015				24,162,657								24,162,657
Balance (in shares) Preferred Stock at Dec. 31, 2015												0