Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets [Abstract]
Cash and due from banks	$ 801,677	$ 947,613
Interest-bearing cash and cash equivalents	354,070	400,652
Trading securities	5,441,038	5,193,505
Investment securities, net of allowance	2,185,744	2,244,153
Available for sale securities	12,653,088	12,286,681
Fair value option securities	19,805	20,671
Restricted equity securities	382,549	423,099
Residential mortgage loans held for sale	75,449	56,935
Loans	24,172,560	23,904,968
Allowance for loan losses	(281,623)	(277,123)
Loans, net of allowance	23,890,937	23,627,845
Premises and equipment, net	628,050	622,223
Receivables	308,736	317,922
Goodwill	1,044,749	1,044,749
Intangible assets, net	56,894	59,979
Mortgage servicing rights	319,330	293,884
Real estate and other repossessed assets, net of allowance	2,860	2,875
Derivative contracts, net	263,493	410,304
Cash surrender value of bank-owned life insurance	410,368	409,548
Receivable on unsettled securities sales	67,854	391,910
Other assets	1,253,689	1,070,282
Total assets	50,160,380	49,824,830
Deposits [Abstract]
Non-interest bearing demand deposits	8,414,056	9,196,493
Interest-bearing deposits: [Abstract]
Transaction	22,748,185	20,964,101
Savings	854,397	847,085
Time	3,366,909	3,012,022
Total deposits	35,383,547	34,019,701
Funds purchased and repurchase agreements	1,261,517	1,122,748
Other borrowings	6,724,652	7,701,552
Subordinated debentures	131,154	131,150
Accrued interest, taxes and expense	318,622	338,996
Derivative contracts, net	438,605	587,473
Due on unsettled securities purchases	264,230	254,057
Other liabilities	506,418	523,734
Total liabilities	45,028,745	44,679,411
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,411,293	1,406,745
Retained earnings	5,259,646	5,211,512
Treasury stock	(932,065)	(876,720)
Accumulated other comprehensive income (loss)	(610,128)	(599,100)
Total shareholders' equity	5,128,751	5,142,442
Non-controlling interests	2,884	2,977
Total equity	5,131,635	5,145,419
Total liabilities and equity	$ 50,160,380	$ 49,824,830