Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest income
Loans and leases, including fees	$ 944,422	$ 956,594	$ 2,843,969	$ 2,983,787
Investment securities
Fully taxable	33,209	38,529	104,736	135,858
Exempt from federal taxes	48	59	113	163
Deposits at banks	14,923	4,163	30,507	27,308
Other	344	1,816	941	6,706
Total interest income	992,946	1,001,161	2,980,266	3,153,822
Interest expense
Savings and interest-checking deposits	7,000	22,403	26,556	126,859
Time deposits	3,573	14,519	15,667	56,274
Deposits at Cayman Islands office		241	201	3,821
Short-term borrowings	2	1	5	26
Long-term borrowings	15,121	20,902	46,852	89,805
Total interest expense	25,696	58,066	89,281	276,785
Net interest income	967,250	943,095	2,890,985	2,877,037
Provision for credit losses	(20,000)	150,000	(60,000)	725,000
Net interest income after provision for credit losses	987,250	793,095	2,950,985	2,152,037
Other income
Brokerage services income	20,490	11,602	43,868	35,194
Trading account and foreign exchange gains	5,563	4,026	18,349	33,332
Gain (loss) on bank investment securities	291	2,773	(22,646)	(11,040)
Other revenues from operations	120,485	107,601	344,114	327,967
Total other income	569,126	520,561	1,588,357	1,537,194
Other expense
Salaries and employee benefits	510,422	478,897	1,530,634	1,474,582
Equipment and net occupancy	80,738	81,080	244,057	237,809
Outside data processing and software	72,782	64,660	213,025	190,446
FDIC assessments	18,810	12,121	50,874	38,599
Advertising and marketing	15,208	11,855	43,200	44,072
Printing, postage and supplies	7,917	9,422	28,367	31,534
Amortization of core deposit and other intangible assets	2,738	3,914	8,213	11,740
Other costs of operations	190,719	164,825	565,753	511,450
Total other expense	899,334	826,774	2,684,123	2,540,232
Income before taxes	657,042	486,882	1,855,219	1,148,999
Income taxes	161,582	114,746	454,441	266,987
Net income	495,460	372,136	1,400,778	882,012
Net income available to common shareholders
Basic	475,958	353,399	1,342,805	827,203
Diluted	$ 475,961	$ 353,400	$ 1,342,812	$ 827,204
Net income per common share
Basic	$ 3.70	$ 2.75	$ 10.44	$ 6.42
Diluted	$ 3.69	$ 2.75	$ 10.43	$ 6.42
Average common shares outstanding
Basic	128,689	128,285	128,632	128,750
Diluted	128,844	128,355	128,786	128,813
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 159,995	$ 153,267	$ 432,062	$ 426,200
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	105,426	91,355	296,721	274,971
Trust Income [Member]
Other income
Revenue from contract with customer	$ 156,876	$ 149,937	$ 475,889	$ 450,570