CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), net [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2013	$ 711,697	$ 105,563	$ 365,333	$ 334,748	$ (20,588)	$ (73,359)
Beginning balance, Shares Outstanding at Dec. 31, 2013		95,245,215
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	44,453			44,453
Total other comprehensive (loss) Income	16,089				16,089
Cash dividends declared	(26,174)			(26,174)
Discount on dividend reinvestment plan purchases	(65)		(65)
Treasury stock acquired	(30,956)					(30,956)
Treasury stock acquired, Shares Outstanding		(3,636,634)
Treasury stock reissued	192		35	0		157
Treasury stock reissued, Shares Outstanding		21,960
Restricted stock	909	$ 0	312	0		597
Restricted stock, Shares Outstanding		92,487
Ending balance at Dec. 31, 2014	716,145	$ 105,563	365,615	353,027	(4,499)	(103,561)
Ending balance, Shares Outstanding at Dec. 31, 2014		91,723,028
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	50,143			50,143
Total other comprehensive (loss) Income	2,113				2,113
Cash dividends declared	(25,089)			(25,089)
Treasury stock acquired	(25,383)					(25,383)
Treasury stock acquired, Shares Outstanding		(2,918,066)
Treasury stock reissued	192		32	0		160
Treasury stock reissued, Shares Outstanding		20,936
Restricted stock	1,425	$ 0	334	0		1,091
Restricted stock, Shares Outstanding		135,370
Ending balance at Dec. 31, 2015	$ 719,546	$ 105,563	365,981	378,081	(2,386)	(127,693)
Ending balance, Shares Outstanding at Dec. 31, 2015	88,961,268	88,961,268
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 59,590			59,590
Total other comprehensive (loss) Income	(4,641)				(4,641)
Cash dividends declared	(24,907)			(24,907)
Treasury stock acquired	(864)					(864)
Treasury stock acquired, Shares Outstanding		(98,687)
Treasury stock reissued	216		39	0		177
Treasury stock reissued, Shares Outstanding		23,148
Restricted stock	989	$ 0	406	0		583
Restricted stock, Shares Outstanding		121,348
Ending balance at Dec. 31, 2016	$ 749,929	$ 105,563	$ 366,426	$ 412,764	$ (7,027)	$ (127,797)
Ending balance, Shares Outstanding at Dec. 31, 2016	89,007,077	89,007,077.000