Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets [Abstract]
Cash and due from banks	$ 729,285	$ 798,757
Interest-bearing cash and cash equivalents	1,162,477	381,816
Trading securities	5,554,040	4,707,975
Investment securities, net of allowance	215,592	244,843
Available for sale securities	13,342,113	13,050,665
Fair value option securities	51,019	114,982
Restricted equity securities	77,542	171,391
Residential mortgage loans held for sale	176,813	252,316
Loans and Leases Receivable, Gross	20,347,936	23,007,520
Allowance for loan losses	(276,680)	(388,640)
Loans, net of allowance	20,071,256	22,618,880
Premises and equipment, net	558,126	551,308
Receivables	171,505	245,880
Goodwill	1,044,749	1,048,091
Intangible assets, net	96,186	113,436
Mortgage servicing rights	133,308	101,172
Real estate and other repossessed assets, net of allowance	28,770	90,526
Derivative contracts, net	1,901,136	810,688
Cash surrender value of bank-owned life insurance	403,369	398,758
Receivable on unsettled securities sales	215,755	62,386
Other assets	990,368	907,218
Total assets	46,923,409	46,671,088
Deposits [Abstract]
Noninterest-bearing demand deposits	14,090,229	12,266,338
Interest-bearing deposits: [Abstract]
Transaction	21,753,110	21,158,422
Savings	900,497	751,992
Time	1,780,715	1,967,128
Total deposits	38,524,551	36,143,880
Funds purchased and repurchase agreements	843,273	1,662,386
Other borrowings	37,426	1,882,970
Subordinated debentures	131,220	276,005
Accrued interest, taxes and expense	220,266	323,667
Derivative contracts, net	739,641	405,779
Due on unsettled securities purchases	614,598	257,627
Other liabilities	415,986	427,213
Total liabilities	41,526,961	41,379,527
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,374,688	1,368,062
Retained earnings	4,366,779	3,973,675
Treasury stock	(521,671)	(411,344)
Accumulated other comprehensive gain	169,172	335,868
Total shareholders’ equity	5,388,973	5,266,266
Non-controlling interests	7,475	25,295
Total equity	5,396,448	5,291,561
Total liabilities and equity	$ 46,923,409	$ 46,671,088