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	80,500			80,500
Other comprehensive income (loss)	(13,140)				(13,140)
Dividends, declared (USD per share)	(25,868)			(25,868)
Treasury stock acquired	(1,136)					(1,136)
Treasury stock acquired, shares		(75,778)
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	422	$ 0	560	0		(138)
Restricted stock, shares		72,500
Stock Issued During Period, Value, Treasury Stock Reissued	2,257
Ending balance at Sep. 30, 2018	972,931	$ 113,915	492,262	493,392	(20,657)	(105,981)
Ending balance, shares at Sep. 30, 2018		100,361,434
Beginning balance at Jun. 30, 2018							$ 960,785	$ 113,915	$ 492,262	$ 477,276	$ (16,561)	$ (106,107)
Beginning balance, shares at Jun. 30, 2018								100,364,567
Net Income	25,149			25,149
Other comprehensive income (loss)	(4,096)				(4,096)
Dividends, declared (USD per share)	(9,033)			(9,033)
Treasury stock acquired	(52)					(52)
Treasury stock acquired, shares		(3,133)
Stock Issued During Period, Value, Treasury Stock Reissued	0		0	0		0
Stock Issued During Period, Shares, Treasury Stock Reissued		0
Restricted stock	178	$ 0	0	0		178
Restricted stock, shares		0
Ending balance at Sep. 30, 2018	972,931	$ 113,915	492,262	493,392	(20,657)	(105,981)
Ending balance, shares at Sep. 30, 2018		100,361,434
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	$ 78,513			78,513
Other comprehensive income (loss)	17,418				17,418
Dividends, declared (USD per share)	(29,562)			(29,562)
Treasury stock acquired	(6,200)					(6,200)
Treasury stock acquired, shares		(482,608)
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	729	$ 0	450	0		279
Restricted stock, shares		78,000
Stock Issued During Period, Value, Treasury Stock Reissued	2,531
Ending balance at Sep. 30, 2019	$ 1,039,030	$ 113,915	493,737	560,360	6,077	(135,059)
Ending balance, shares at Sep. 30, 2019	98,319,081	98,319,081
Beginning balance at Jun. 30, 2019	$ 1,021,831	$ 113,915	493,737	543,566	3,693	(133,080)
Beginning balance, shares at Jun. 30, 2019		98,499,937
Net Income	26,644			26,644
Other comprehensive income (loss)	2,384				2,384
Dividends, declared (USD per share)	(9,850)			(9,850)
Treasury stock acquired	(2,240)					(2,240)
Treasury stock acquired, shares		(180,856)
Stock Issued During Period, Value, Treasury Stock Reissued	0		0	0		0
Stock Issued During Period, Shares, Treasury Stock Reissued		0
Restricted stock	261	$ 0	0	0		261
Restricted stock, shares		0
Ending balance at Sep. 30, 2019	$ 1,039,030	$ 113,915	$ 493,737	$ 560,360	$ 6,077	$ (135,059)
Ending balance, shares at Sep. 30, 2019	98,319,081	98,319,081