Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock Outstanding	Common Stock	Value of Shares Held in Rabbi Trust at Cost	Deferred Compensation Obligation	Additional Paid in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	[1]		$ 0							$ 831		$ (831)
Beginning balance at Dec. 31, 2017		$ 943,809			$ 273	$ (4,590)	$ 4,590	$ 479,430	$ 465,937		$ (1,831)
Beginning balance (in shares) at Dec. 31, 2017				27,450,190
Prior Period Reclassification Adjustment											(397)
Net income		121,622							$ 121,622
Other comprehensive income		1,886									1,886
Common Stock, Dividends, Per Share, Declared									$ 1.52
Common dividend declared		(42,051)							$ (42,051)
Common stock issued for acquisition		42,474			5			42,469
Common stock issued for acquisition (in shares)				528,353
Proceeds from exercise of stock options, net of cash paid		184						184
Proceeds from exercise of stock options (in shares)				23,195
Stock based compensation		4,225						4,225
Restricted stock awards issued, net of awards surrendered (in shares)				43,383
Restricted stock awards issued, net of awards surrendered		(1,371)			1			(1,372)
Stock Issued During Period, Shares, Other				35,287
Stock Issued During Period, Value, Other		2,712						2,712
Increase (Decrease) in Deferred Compensation						(128)	128
Ending balance (in shares) at Dec. 31, 2018				28,080,408
Ending balance at Dec. 31, 2018		1,073,490			279	(4,718)	4,718	527,648	546,736		(1,173)
Net income		165,175							$ 165,175
Other comprehensive income		19,342									19,342
Common Stock, Dividends, Per Share, Declared									$ 1.76
Common dividend declared		(57,729)							$ (57,729)
Common stock issued for acquisition		499,693			61			499,632
Common stock issued for acquisition (in shares)				6,166,010
Proceeds from exercise of stock options, net of cash paid		281			0			281
Proceeds from exercise of stock options (in shares)				14,646
Stock based compensation		4,403						4,403
Restricted stock awards issued, net of awards surrendered (in shares)				50,080
Restricted stock awards issued, net of awards surrendered		(1,463)			1			(1,464)
Stock Issued During Period, Shares, Other				66,244
Stock Issued During Period, Value, Other		4,951			1			4,950
Increase (Decrease) in Deferred Compensation		$ 0
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits						(17)	17
Ending balance (in shares) at Dec. 31, 2019		34,377,388		34,377,388
Ending balance at Dec. 31, 2019		$ 1,708,143			342	(4,735)	4,735	1,035,450	654,182		18,169
Net income		121,167							$ 121,167
Other comprehensive income		22,526									22,526
Common Stock, Dividends, Per Share, Declared									$ 1.84
Common dividend declared		(60,878)							$ (60,878)
Common stock issued for acquisition		0
Proceeds from exercise of stock options (in shares)				8,873
Stock based compensation		4,123						4,123
Restricted stock awards issued, net of awards surrendered (in shares)				47,182
Restricted stock awards issued, net of awards surrendered		(1,187)			1			(1,188)
Stock Issued During Period, Shares, Other				32,249
Stock Issued During Period, Value, Other		2,132						2,132
Stock Repurchased During Period, Shares				(1,500,000)
Increase (Decrease) in Deferred Compensation		$ 0
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits						1,669	(1,669)
Ending balance (in shares) at Dec. 31, 2020		32,965,692		32,965,692
Ending balance at Dec. 31, 2020		$ 1,702,685			328	$ (3,066)	$ 3,066	945,638	$ 716,024		$ 40,695
Stock Repurchased During Period, Value, as a result of Stock Options Exercised		197						197
Stock Repurchased During Period, Value		(95,091)			$ (15)			$ (95,076)
Off-Balance Sheet, Credit Loss, Liability, Change in Method, Credit Loss Expense (Reversal)		(1,000)
Off-Balance Sheet, Credit Loss, Liability, Change in Method, Credit Loss Expense (Reversal), net of tax.		736
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method, net of tax.		$ 817
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	[2]		$ 1,553							$ 1,553

[1] Represents adjustment needed to reflect the cumulative impact on retained earnings for the classification and measurement of investments in equity securities. Pursuant to the Company's adoption of Accounting Standards Update 2016-01, the Company's investments in equity securities will no longer be classified as available for sale, therefore the Company was required to reclassify the net unrealized gain recognized on the change in fair value of these equity securities from other comprehensive income to retained earnings.

[2] Represents adjustment needed to reflect the cumulative impact on retained earnings pursuant to the Company's adoption of Accounting Standards Update 2016-13. The adjustment presented includes $1.1 million ($817,000, net of tax) attributable to the change in accounting methodology for estimating the allowance for credit losses and $1.0 million ($736,000, net of tax) related to the reserve for unfunded commitments resulting from the Company's adoption of the standard. Amount shown in the table above is presented net of tax.