Parent Company Condensed Financial Statements - Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of cash flows
Net income	$ 1,128,083	$ 872,981	$ 567,797
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income (benefit) tax expense	(43,988)	4,762	(41,515)
Net change in other assets	187,512	124,496	(340,566)
Net change in other liabilities	461,385	(63,360)	136,260
Net cash provided by operating activities	2,066,022	1,168,422	692,644
CASH FLOWS FROM INVESTING ACTIVITIES
Net increase in investments in tax credit investments	(167,303)	(189,836)	(154,887)
Distributions received from equity method investees	18,221	14,440	15,901
Net cash (used in) provided by investing activities	(4,582,892)	(9,117,204)	(6,873,736)
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements	3,178	2,573	2,326
Stocks tendered for payment of withholding taxes	(19,087)	(15,702)	(8,253)
Repurchase of common stocks pursuant to the Stock Repurchase Program	(99,990)	0	(145,966)
Cash dividends paid	(228,381)	(188,762)	(158,222)
Net cash provided by financing activities	2,114,210	7,835,045	6,908,908
Net (decrease) increase in cash and cash equivalents	(431,151)	(105,036)	756,822
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	3,912,935	4,017,971	3,261,149
CASH AND CASH EQUIVALENTS, END OF YEAR	3,481,784	3,912,935	4,017,971
Parent Company
Statement of cash flows
Net income	1,128,083	872,981	567,797
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiaries, principally bank	(897,069)	(680,958)	(65,046)
Amortization expense	1,333	1,877	1,523
Deferred income (benefit) tax expense	(2,193)	2,721	491
Net change in other assets	4,250	(5,685)	40
Net change in other liabilities	779	(81,706)	77,052
Net cash provided by operating activities	235,183	109,230	581,857
CASH FLOWS FROM INVESTING ACTIVITIES
Net increase in investments in tax credit investments	(1,612)	(346)	(172)
Distributions received from equity method investees	410	436	4,096
Net increase in investments in and advances to nonbank subsidiaries	(6,188)	(1,476)	(2,732)
Net cash (used in) provided by investing activities	(7,390)	(1,386)	1,192
Common stock:
Proceeds from issuance pursuant to various stock compensation plans and agreements	3,178	2,573	2,326
Stocks tendered for payment of withholding taxes	(19,087)	(15,702)	(8,253)
Repurchase of common stocks pursuant to the Stock Repurchase Program	(99,990)	0	(145,966)
Cash dividends paid	(228,381)	(188,762)	(158,222)
Net cash provided by financing activities	(344,280)	(201,891)	(310,115)
Net (decrease) increase in cash and cash equivalents	(116,487)	(94,047)	272,934
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	345,018	439,065	166,131
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 228,531	$ 345,018	$ 439,065