Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect Period Of Adoption Adjustment [Member]	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect Period Of Adoption Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2018	$ 1,591,453		$ 13,717	$ 309,545	$ 1,323,870		$ (55,679)
Balance (in shares) at Dec. 31, 2018			65,834,395
Net income per consolidated statements of income	150,460				150,460
Other comprehensive income (loss), net of tax	32,079						(32,079)
Cash dividends paid on common stock ($0.92 per share)	(59,804)				(59,804)
Shares withheld to pay taxes, long-term incentive plan	(1,658)		$ 28	(1,686)
Shares withheld to pay taxes, long-term incentive plan (in shares)			134,564
Repurchase and retirement of common stock	(56,615)		$ (369)	(56,246)
Repurchase and retirement of common stock (in shares)			(1,768,848)
Compensation expense, long-term incentive plan	4,787			4,787
Balance at Dec. 31, 2019	$ 1,660,702	$ (19,949)	$ 13,376	256,400	1,414,526	$ (19,949)	(23,600)
Balance (in shares) at Dec. 31, 2019			64,200,111
Accounting standards update [Extensible List]	Accounting Standards Update 2016-13 [Member]
Net income per consolidated statements of income	$ 160,025				160,025
Other comprehensive income (loss), net of tax	22,549						22,549
Cash dividends paid on common stock ($0.92 per share)	(58,769)				(58,769)
Shares withheld to pay taxes, long-term incentive plan	(1,100)		$ 23	(1,123)
Shares withheld to pay taxes, long-term incentive plan (in shares)			111,373
Repurchase and retirement of common stock	(27,538)		$ (184)	(27,354)
Repurchase and retirement of common stock (in shares)			(886,958)
Compensation expense, long-term incentive plan	5,197			5,197
Balance at Dec. 31, 2020	$ 1,741,117		$ 13,215	233,120	1,495,833		(1,051)
Balance (in shares) at Dec. 31, 2020	63,424,526		63,424,526
Net income per consolidated statements of income	$ 147,365				147,365
Other comprehensive income (loss), net of tax	(31,509)						(31,509)
Cash dividends paid on common stock ($0.92 per share)	(58,085)				(58,085)
Shares withheld to pay taxes, long-term incentive plan	(1,379)		$ 28	(1,407)
Shares withheld to pay taxes, long-term incentive plan (in shares)			133,907
Repurchase and retirement of common stock	(61,799)		$ (398)	(61,401)
Repurchase and retirement of common stock (in shares)			(1,909,754)
Compensation expense, long-term incentive plan	5,601			5,601
Balance at Dec. 31, 2021	$ 1,741,311		$ 12,845	$ 175,913	$ 1,585,113		$ (32,560)
Balance (in shares) at Dec. 31, 2021	61,648,679		61,648,679