Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - 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, 2014	$ 716,145	$ 105,563	$ 365,615	$ 353,027	$ (4,499)	$ (103,561)
Beginning balance, shares at Dec. 31, 2014		91,723,028
Net Income	40,082			40,082
Other comprehensive income (loss)	9,460				9,460
Dividends, declared (USD per share)	(18,862)			(18,862)
Treasury stock acquired	(25,383)					(25,383)
Treasury stock acquired, shares		(2,918,066)
Restricted stock	1,134	$ 0	303	0		831
Restricted stock, shares		135,370
Ending balance at Sep. 30, 2015	722,768	$ 105,563	365,950	374,247	4,961	(127,953)
Ending balance, shares at Sep. 30, 2015		88,961,268
Stock Issued During Period, Shares, Treasury Stock Reissued		20,936
Stock Issued During Period, Value, Treasury Stock Reissued	192		32	0		160
Beginning balance at Dec. 31, 2015	$ 719,546	$ 105,563	365,981	378,081	(2,386)	(127,693)
Beginning balance, shares at Dec. 31, 2015	88,961,268	88,961,268
Net Income	$ 41,676			41,676
Other comprehensive income (loss)	9,148				9,148
Dividends, declared (USD per share)	(18,678)			(18,678)
Treasury stock acquired	(864)					(864)
Treasury stock acquired, shares		(98,687)
Restricted stock	743	$ 0	271	0		472
Restricted stock, shares		106,348
Ending balance at Sep. 30, 2016	$ 751,787	$ 105,563	366,291	401,079	$ 6,762	(127,908)
Ending balance, shares at Sep. 30, 2016	88,992,077	88,992,077
Stock Issued During Period, Shares, Treasury Stock Reissued		23,148
Stock Issued During Period, Value, Treasury Stock Reissued	$ 216		$ 39	$ 0		$ 177