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]	Previously Reported [Member]	Previously Reported [Member] Common Stock [Member]	Previously Reported [Member] Additional Paid-in Capital [Member]	Previously Reported [Member] Retained Earnings [Member]	Previously Reported [Member] Accumulated Other Comprehensive Income (Loss), net [Member]	Previously Reported [Member] Treasury Stock [Member]	Effect of ASU Adoption [Member] Accumulated Other Comprehensive Income (Loss), net [Member]
Cumulative effect of adoption of ASU 2018-02	$ 0			$ 1,344	$ (1,344)
Beginning balance at Dec. 31, 2017	888,127	$ 113,915	$ 470,123	438,760	(7,517)	$ (127,154)	$ 888,127	$ 113,915	$ 470,123	$ 437,416	$ (6,173)	$ (127,154)
Beginning balance, shares at Dec. 31, 2017		97,456,478						97,456,478
Net Income	55,351			55,351
Other comprehensive income (loss)	(9,044)				(9,044)
Dividends, declared (USD per share)	(16,835)			(16,835)
Treasury stock acquired	(1,084)					(1,084)
Treasury stock acquired, shares		(72,645)
Stock Issued During Period, Value, Treasury Stock Reissued	44,026		21,579	0		22,447
Stock Issued During Period, Shares, Treasury Stock Reissued		2,908,234
Restricted stock	244	$ 0	560	0		(316)
Restricted stock, shares		72,500
Stock Issued During Period, Value, Treasury Stock Reissued	2,257
Ending balance at Jun. 30, 2018	960,785	$ 113,915	492,262	477,276	(16,561)	(106,107)
Ending balance, shares at Jun. 30, 2018		100,364,567
Beginning balance at Mar. 31, 2018							$ 899,349	$ 113,915	$ 471,768	$ 454,227	$ (13,009)	$ (127,552)
Beginning balance, shares at Mar. 31, 2018								97,603,151
Net Income	32,081			32,081
Other comprehensive income (loss)	(3,552)				(3,552)
Dividends, declared (USD per share)	(9,032)			(9,032)
Treasury stock acquired	(5)					(5)
Treasury stock acquired, shares		(338)
Stock Issued During Period, Value, Treasury Stock Reissued	41,769		20,471	0		21,298
Stock Issued During Period, Shares, Treasury Stock Reissued		2,758,754
Restricted stock	175	$ 0	23	0		152
Restricted stock, shares		3,000
Ending balance at Jun. 30, 2018	960,785	$ 113,915	492,262	477,276	(16,561)	(106,107)
Ending balance, shares at Jun. 30, 2018		100,364,567
Cumulative effect of adoption of ASU 2018-02													$ 0
Beginning balance at Dec. 31, 2018	$ 975,389	$ 113,915	492,273	511,409	(11,341)	(130,867)
Beginning balance, shares at Dec. 31, 2018	98,518,668	98,518,668
Net Income	$ 51,869			51,869
Other comprehensive income (loss)	15,034				15,034
Dividends, declared (USD per share)	(19,712)			(19,712)
Treasury stock acquired	(3,960)					(3,960)
Treasury stock acquired, shares		(301,752)
Stock Issued During Period, Value, Treasury Stock Reissued	2,743		1,014	0		1,729
Stock Issued During Period, Shares, Treasury Stock Reissued		205,021
Restricted stock	468	$ 0	450	0		18
Restricted stock, shares		78,000
Stock Issued During Period, Value, Treasury Stock Reissued	2,531
Ending balance at Jun. 30, 2019	$ 1,021,831	$ 113,915	493,737	543,566	3,693	(133,080)
Ending balance, shares at Jun. 30, 2019	98,499,937	98,499,937
Beginning balance at Mar. 31, 2019	$ 998,019	$ 113,915	493,664	526,136	(4,102)	(131,594)
Beginning balance, shares at Mar. 31, 2019		98,625,806
Net Income	27,280			27,280
Other comprehensive income (loss)	7,795				7,795
Dividends, declared (USD per share)	(9,850)			(9,850)
Treasury stock acquired	(1,886)					(1,886)
Treasury stock acquired, shares		(142,190)
Stock Issued During Period, Value, Treasury Stock Reissued	212		73	0		139
Stock Issued During Period, Shares, Treasury Stock Reissued		16,321
Restricted stock	261	$ 0	0	0		261
Restricted stock, shares		0
Ending balance at Jun. 30, 2019	$ 1,021,831	$ 113,915	$ 493,737	$ 543,566	$ 3,693	$ (133,080)
Ending balance, shares at Jun. 30, 2019	98,499,937	98,499,937