Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets [Abstract]
Cash and due from banks	$ 762,453	$ 735,836
Interest-bearing cash and cash equivalents	485,319	522,985
Trading securities	1,196,105	1,623,921
Investment securities, net of allowance	267,988	293,418
Available for sale securities	12,475,919	11,269,643
Fair value option securities	722,657	1,098,577
Restricted equity securities	125,683	460,552
Residential mortgage loans held for sale	319,357	182,271
Loans	24,155,890	21,750,987
Allowance for loan losses	(435,597)	(210,759)
Loans, net of allowance	23,720,293	21,540,228
Premises and equipment, net	550,230	535,519
Receivables	226,934	231,811
Goodwill	1,048,091	1,048,091
Intangible assets, net	123,595	125,271
Mortgage servicing rights	97,971	201,886
Real estate and other repossessed assets, net of allowance	35,330	20,359
Derivative contracts, net	651,553	323,375
Cash surrender value of bank-owned life insurance	393,741	389,879
Receivable on unsettled securities sales	1,863,719	1,020,404
Other assets	752,936	547,995
Total assets	45,819,874	42,172,021
Deposits [Abstract]
Noninterest-bearing demand deposits	11,992,165	9,461,291
Interest-bearing deposits: [Abstract]
Transaction	18,850,418	15,391,752
Savings	696,971	550,276
Time	2,352,760	2,217,849
Total deposits	33,892,314	27,621,168
Funds purchased and repurchase agreements	1,357,602	3,818,350
Other borrowings	3,173,563	4,527,055
Subordinated debentures	275,973	275,923
Accrued interest, taxes and expense	365,634	259,701
Derivative contracts, net	610,020	251,128
Due on unsettled securities purchases	599,510	182,547
Other liabilities	440,835	372,230
Total liabilities	40,715,451	37,308,102
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,357,706	1,350,995
Retained earnings	3,737,862	3,729,778
Treasury stock	(368,894)	(329,906)
Accumulated other comprehensive gain	370,316	104,923
Total shareholders’ equity	5,096,995	4,855,795
Non-controlling interests	7,428	8,124
Total equity	5,104,423	4,863,919
Total liabilities and equity	$ 45,819,874	$ 42,172,021