CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings		Accumulated Other Comprehensive (Loss)/Income		Reclassifications Related to Funded Status of Pension	Reclassifications Related to Unrealized Gains on Available for Sale Securities	Treasury Stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings		Cumulative Effect, Period of Adoption, Adjustment Accumulated Other Comprehensive (Loss)/Income	[1]
Beginning balance at Dec. 31, 2017	$ 884,031	$ 90,326	$ 216,106	$ 628,107		$ (18,427)				$ (32,081)
Beginning balance (ASU No. 2016-01) at Dec. 31, 2017											$ 0	$ 862	[1]	$ (862)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	105,334			105,334
Other comprehensive income (loss), net of tax	(391)					(391)
Reclassification of tax effects from the Tax Act	0			3,427	[2]	(3,427)	[2]
Reclassification of tax effects from the Tax Act | ASU No. 2018-02								$ (3,660)	$ 233
Repurchase of warrant	(7,652)		(7,652)
Cash dividends declared	(34,539)			(34,539)
Treasury stock repurchased	(12,256)									(12,256)
Treasury stock issued	(657)			(1,372)						715
Recognition of restricted stock compensation expense	1,891		1,891
Ending balance at Dec. 31, 2018	$ 935,761	90,326	210,345	701,819		(23,107)				(43,622)	167	167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Net Income	$ 98,234			98,234
Other comprehensive income (loss), net of tax	11,437					11,437
Cash dividends declared	(37,360)			(37,360)
Common stock issuance cost	(176)		(176)
Common stock issued in acquisition	200,631	13,297	187,334
Treasury stock repurchased	(18,222)									(18,222)
Treasury stock issued	(915)			(1,777)						862
Recognition of restricted stock compensation expense	2,441		2,441
Ending balance at Dec. 31, 2019	$ 1,191,998	103,623	399,944	761,083		(11,670)				(60,982)	$ (22,590)	$ (22,590)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net Income	$ 21,040			21,040
Other comprehensive income (loss), net of tax	20,641					20,641
Cash dividends declared	(43,949)			(43,949)
Treasury stock repurchased	(12,559)									(12,559)
Treasury stock issued	(594)			(5,523)						4,929
Recognition of restricted stock compensation expense	724		724
Ending balance at Dec. 31, 2020	$ 1,154,711	$ 103,623	$ 400,668	$ 710,061		$ 8,971				$ (68,612)

[1] Reclassification due to the adoption of ASU No. 2016-01, related to changes in fair value for equity securities reclassified out of accumulated other comprehensive income.

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