Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Assets [Abstract]
Cash and due from banks	$ 875,714	$ 943,810
Interest-bearing cash and cash equivalents	571,616	457,906
Trading securities	5,442,364	4,464,161
Investment securities, net of allowance	2,374,071	2,513,687
Available for sale securities	11,938,523	11,493,860
Fair value option securities	212,321	296,590
Restricted equity securities	330,086	299,651
Residential mortgage loans held for sale	94,820	75,272
Loans	23,237,659	22,557,150
Allowance for loan losses	(262,714)	(235,704)
Loans, net of allowance	22,974,945	22,321,446
Premises and equipment, net	617,918	565,175
Receivables	263,915	273,815
Goodwill	1,044,749	1,044,749
Intangible assets, net	69,246	76,131
Mortgage servicing rights	304,722	277,608
Real estate and other repossessed assets, net of allowance	4,227	14,304
Derivative contracts, net	353,037	880,343
Cash surrender value of bank-owned life insurance	411,084	406,751
Receivable on unsettled securities sales	133,909	31,004
Other assets	1,220,653	1,354,379
Total assets	49,237,920	47,790,642
Deposits [Abstract]
Noninterest-bearing demand deposits	10,782,548	13,395,337
Interest-bearing deposits: [Abstract]
Transaction	18,907,981	18,659,115
Savings	897,937	964,411
Time	2,706,377	1,461,842
Total deposits	33,294,843	34,480,705
Funds purchased and repurchase agreements	5,446,864	2,270,377
Other borrowings	3,777,056	4,736,908
Subordinated debentures	131,154	131,205
Accrued interest, taxes and expense	228,797	296,870
Derivative contracts, net	550,653	554,900
Due on unsettled securities purchases	400,430	147,470
Other liabilities	540,726	484,849
Total liabilities	44,370,523	43,103,284
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,401,509	1,390,395
Retained earnings	5,065,733	4,824,164
Treasury stock	(766,721)	(694,960)
Accumulated other comprehensive income (loss)	(836,672)	(836,955)
Total shareholders' equity	4,863,854	4,682,649
Non-controlling interests	3,543	4,709
Total equity	4,867,397	4,687,358
Total liabilities and equity	$ 49,237,920	$ 47,790,642