Consolidated Statements of Changes in Shareholders' Equity (unaudited) - USD ($) $ in Thousands	Common Stock	Surplus	Retained Earnings Cumulative Effect of Adoption of ASU	Retained Earnings	Accumulated Other Comprehensive Loss	Cumulative Effect of Adoption of ASU	Total
Balance at Dec. 31, 2022	$ 189,261	$ 4,215,712		$ 1,347,042	$ (677,088)		$ 5,074,927
Balance (in shares) at Dec. 31, 2022	75,704,563
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)				387,517			387,517
Other comprehensive income (loss), net of tax effects					(138,801)		(138,801)
Total comprehensive income (loss)							248,716
Cash dividends declared on common stock per share				(115,400)			(115,400)
Cash dividend equivalents paid on restricted stock units				(1,079)			(1,079)
Employee stock purchases	$ 52	1,304					1,356
Employee stock purchases (in shares)	20,903
Stock options exercised	$ 68	1,324					1,392
Stock options exercised (in shares)	27,156
Restricted stock awards (forfeits)	$ (7)	7
Restricted stock awards (forfeits) (in shares)	(2,559)
Stock issued pursuant to restricted stock units	$ 927	(927)
Stock issued pursuant to restricted stock units (in shares)	370,493
Common stock repurchased	$ (258)	(7,151)					(7,409)
Common stock repurchased (in shares)	(103,190)
Share-based compensation expense		28,484					28,484
Balance at Sep. 30, 2023	$ 190,043	4,238,753		1,618,080	(815,889)		5,230,987
Balance (in shares) at Sep. 30, 2023	76,017,366
Balance at Jun. 30, 2023	$ 189,990	4,228,910		1,533,508	(662,398)		5,290,010
Balance (in shares) at Jun. 30, 2023	75,995,979
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)				124,144			124,144
Other comprehensive income (loss), net of tax effects					(153,491)		(153,491)
Total comprehensive income (loss)							(29,347)
Cash dividends declared on common stock per share				(39,526)			(39,526)
Cash dividend equivalents paid on restricted stock units				(46)			(46)
Employee stock purchases	$ 28	681					709
Employee stock purchases (in shares)	11,341
Stock options exercised	$ 9	210					219
Stock options exercised (in shares)	3,640
Restricted stock awards (forfeits)	$ (1)	1
Restricted stock awards (forfeits) (in shares)	(206)
Stock issued pursuant to restricted stock units	$ 30	(30)
Stock issued pursuant to restricted stock units (in shares)	11,709
Common stock repurchased	$ (13)	(374)					(387)
Common stock repurchased (in shares)	(5,097)
Share-based compensation expense		9,355					9,355
Balance at Sep. 30, 2023	$ 190,043	4,238,753		1,618,080	(815,889)		5,230,987
Balance (in shares) at Sep. 30, 2023	76,017,366
Balance at Dec. 31, 2023	$ 190,055	4,240,413		1,685,166	(582,536)		$ 5,533,098
Balance (in shares) at Dec. 31, 2023	76,022,039						76,022,039
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)				390,605			$ 390,605
Other comprehensive income (loss), net of tax effects					102,896		102,896
Total comprehensive income (loss)							493,501
Cash dividends declared on common stock per share				(120,391)			(120,391)
Cash dividend equivalents paid on restricted stock units				(1,260)			(1,260)
Employee stock purchases	$ 49	1,435					1,484
Employee stock purchases (in shares)	19,484
Stock options exercised	$ 126	3,867					3,993
Stock options exercised (in shares)	50,155
Restricted stock awards (forfeits)	$ (2)	2
Restricted stock awards (forfeits) (in shares)	(316)
Stock issued pursuant to restricted stock units	$ 950	(950)
Stock issued pursuant to restricted stock units (in shares)	380,151
Stock issued in lieu of cash - directors fees	$ 6	180					186
Stock issued in lieu of cash - directors fees (in shares)	2,211
Common stock repurchased - buyback plan	$ (250)	(7,735)					(7,985)
Common stock repurchased - buyback plan (in shares)	(100,000)
Common stock repurchased	$ (260)	(8,438)					(8,698)
Common stock repurchased (in shares)	(104,147)
Share-based compensation expense		20,898					20,898
Balance (ASU 2023-02) at Sep. 30, 2024			$ (10,246)			$ (10,246)
Balance at Sep. 30, 2024	$ 190,674	4,249,672		1,943,874	(479,640)		$ 5,904,580
Balance (in shares) at Sep. 30, 2024	76,269,577						76,269,577
Balance at Jun. 30, 2024	$ 190,489	4,238,192		1,841,933	(620,211)		$ 5,650,403
Balance (in shares) at Jun. 30, 2024	76,195,723
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)				143,179			143,179
Other comprehensive income (loss), net of tax effects					140,571		140,571
Total comprehensive income (loss)							283,750
Cash dividends declared on common stock per share				(41,174)			(41,174)
Cash dividend equivalents paid on restricted stock units				(64)			(64)
Employee stock purchases	$ 26	728					754
Employee stock purchases (in shares)	10,392
Stock options exercised	$ 107	3,445					3,552
Stock options exercised (in shares)	42,707
Stock issued pursuant to restricted stock units	$ 66	(66)
Stock issued pursuant to restricted stock units (in shares)	26,476
Stock issued in lieu of cash - directors fees	$ 3	90					93
Stock issued in lieu of cash - directors fees (in shares)	1,063
Common stock repurchased	$ (17)	(588)					(605)
Common stock repurchased (in shares)	(6,784)
Share-based compensation expense		7,871					7,871
Balance (ASU 2023-02) at Sep. 30, 2024			$ (10,246)			$ (10,246)
Balance at Sep. 30, 2024	$ 190,674	$ 4,249,672		$ 1,943,874	$ (479,640)		$ 5,904,580
Balance (in shares) at Sep. 30, 2024	76,269,577						76,269,577