Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets [Abstract]
Cash and due from banks	$ 792,371	$ 943,810
Interest-bearing cash and cash equivalents	571,613	457,906
Trading securities	2,294,358	4,464,161
Investment securities, net of allowance	2,448,136	2,513,687
Available for sale securities	11,937,841	11,493,860
Fair value option securities	326,390	296,590
Restricted equity securities	288,181	299,651
Residential mortgage loans held for sale	74,175	75,272
Loans	22,750,053	22,557,150
Allowance for loan losses	(249,460)	(235,704)
Loans, net of allowance	22,500,593	22,321,446
Premises and equipment, net	623,112	565,175
Receivables	265,680	273,815
Goodwill	1,044,749	1,044,749
Intangible assets, net	72,689	76,131
Mortgage servicing rights	299,803	277,608
Real estate and other repossessed assets, net of allowance	12,651	14,304
Derivative contracts, net	394,291	880,343
Cash surrender value of bank-owned life insurance	408,614	406,751
Receivable on unsettled securities sales	18,186	31,004
Other assets	1,150,689	1,354,379
Total assets	45,524,122	47,790,642
Deposits [Abstract]
Noninterest-bearing demand deposits	11,606,975	13,395,337
Interest-bearing deposits: [Abstract]
Transaction	18,434,489	18,659,115
Savings	962,673	964,411
Time	1,576,610	1,461,842
Total deposits	32,580,747	34,480,705
Funds purchased and repurchase agreements	1,599,724	2,270,377
Other borrowings	4,735,885	4,736,908
Subordinated debentures	131,148	131,205
Accrued interest, taxes and expense	268,449	296,870
Derivative contracts, net	510,483	554,900
Due on unsettled securities purchases	262,492	147,470
Other liabilities	557,167	484,849
Total liabilities	40,646,095	43,103,284
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,397,096	1,390,395
Retained earnings	4,950,176	4,824,164
Treasury stock	(743,937)	(694,960)
Accumulated other comprehensive income (loss)	(728,554)	(836,955)
Total shareholders' equity	4,874,786	4,682,649
Non-controlling interests	3,241	4,709
Total equity	4,878,027	4,687,358
Total liabilities and equity	$ 45,524,122	$ 47,790,642