CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss)/Income	Reclassifications Related to Funded Status of Pension	Reclassifications Related to Unrealized Gains on Available for Sale Securities
Beginning Balance at Dec. 31, 2017		$ 884,031	$ 90,326	$ 216,106	$ 628,107	$ (32,081)	$ (18,427)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		78,480			78,480
Other comprehensive income (loss), net of tax		(10,537)					(10,537)
Reclassification of tax effects from the Tax Act | ASU No. 2018-02	[1]	0			3,427		(3,427)	$ (3,660)	$ 233
Cash dividends declared		(25,115)			(25,115)
Treasury stock issued for restricted awards		(657)			(1,400)	743
Repurchase of warrant		(7,652)		(7,652)
Recognition of restricted stock compensation expense		1,231		1,231
Ending Balance at Sep. 30, 2018		919,781	90,326	209,685	684,361	(31,338)	(33,253)
Beginning Balance at Jun. 30, 2018		907,133	90,326	216,885	662,112	(31,245)	(30,945)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		30,881			30,881
Other comprehensive income (loss), net of tax		(2,308)					(2,308)
Cash dividends declared		(8,724)			(8,724)
Treasury stock issued for restricted awards		(1)			92	(93)
Repurchase of warrant		(7,652)		(7,652)
Recognition of restricted stock compensation expense		452		452
Ending Balance at Sep. 30, 2018		919,781	90,326	209,685	684,361	(31,338)	(33,253)
Beginning Balance at Dec. 31, 2018		935,761	90,326	210,345	701,819	(43,622)	(23,107)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		75,965			75,965
Other comprehensive income (loss), net of tax		15,794					15,794
Cash dividends declared		(27,798)			(27,798)
Treasury stock issued for restricted awards		(915)			(1,873)	958
Issuance Cost		(125)		(125)
Repurchase of common stock		(18,222)				(18,222)
Recognition of restricted stock compensation expense		1,820		1,820
Ending Balance at Sep. 30, 2019		982,447	90,326	212,040	748,280	(60,886)	(7,313)
Beginning Balance at Jun. 30, 2019		964,953	90,326	211,325	730,577	(57,756)	(9,519)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		26,936			26,936
Other comprehensive income (loss), net of tax		2,206					2,206
Cash dividends declared		(9,239)			(9,239)
Treasury stock issued for restricted awards		(24)			6	(30)
Issuance Cost		(125)		(125)
Repurchase of common stock		(3,100)				(3,100)
Recognition of restricted stock compensation expense		840		840
Ending Balance at Sep. 30, 2019		$ 982,447	$ 90,326	$ 212,040	$ 748,280	$ (60,886)	$ (7,313)

[1] Reclassification due to the adoption of ASU No. 2018-02, $(3,660) relates to funded status of pension and $233 relates to net unrealized gains on available-for-sale securities.