Parent Company Condensed Financial Statements - Schedule of Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of cash flows
Net income	$ 1,325,188	$ 1,165,586	$ 1,161,161
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense	(7,775)	(14,283)	(49,139)
Net change in other assets	(97,306)	63,743	(146,270)
Net change in other liabilities	(167,970)	(242,443)	105,304
Other operating activities, net	(9,099)	1,846	11,508
Net cash provided by operating activities	1,501,700	1,411,667	1,424,909
AFS debt securities:
Proceeds from maturities	3,851,138	1,547,058	1,470,819
Purchases	(6,939,256)	(7,599,454)	(1,549,846)
Other investing activities, net	4,527	8,894	(88,262)
Net cash used in investing activities	(5,476,505)	(6,295,203)	(4,247,161)
Long-term debt:
Repayment of junior subordinated debt	(836)	(117,437)	(871)
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements	3,212	3,023	3,208
Stock tendered for payment of withholding taxes	(19,239)	(14,877)	(23,751)
Repurchase of common stock pursuant to the stock repurchase program	(115,590)	(143,082)	(82,174)
Cash dividends paid	(334,041)	(308,478)	(274,554)
Net cash provided by financing activities	2,897,225	5,527,526	3,962,454
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(1,062,603)	635,758	1,133,200
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	5,250,742	4,614,984	3,481,784
CASH AND CASH EQUIVALENTS, END OF YEAR	4,188,139	5,250,742	4,614,984
Parent Company
Statement of cash flows
Net income	1,325,188	1,165,586	1,161,161
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiaries, principally bank	(584,292)	(635,868)	(470,740)
Deferred income tax expense	62	2,788	948
Net change in other assets	(5,549)	(6,912)	(4,160)
Net change in other liabilities	(1,686)	(802)	(47)
Other operating activities, net	1,083	1,265	2,443
Net cash provided by operating activities	734,806	526,057	689,605
AFS debt securities:
Proceeds from maturities	1,945,000	0	0
Purchases	(1,944,333)	0	0
Redemption of trust preferred securities	0	3,558	0
Other investing activities, net	(732)	(494)	(95,095)
Net cash used in investing activities	(65)	3,064	(95,095)
Long-term debt:
Repayment of junior subordinated debt	0	(116,558)	0
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements	3,212	3,023	3,208
Stock tendered for payment of withholding taxes	(19,239)	(14,877)	(23,751)
Repurchase of common stock pursuant to the stock repurchase program	(115,590)	(143,082)	(82,174)
Cash dividends paid	(334,041)	(308,478)	(274,554)
Net cash provided by financing activities	(465,658)	(579,972)	(377,271)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	269,083	(50,851)	217,239
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	394,919	445,770	228,531
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 664,002	$ 394,919	$ 445,770