Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest income
Loans and leases, including fees	$ 1,119,662	$ 1,060,832	$ 3,363,152	$ 3,065,272
Investment securities
Fully taxable	69,059	80,118	225,048	244,989
Exempt from federal taxes	98	153	270	573
Deposits at banks	40,388	26,000	104,120	66,546
Other	262	272	1,101	1,050
Total interest income	1,229,469	1,167,375	3,693,691	3,378,430
Interest expense
Savings and interest-checking deposits	104,724	56,156	272,419	145,421
Time deposits	25,456	12,976	71,468	35,274
Deposits at Cayman Islands office	6,218	1,556	16,995	2,479
Short-term borrowings	6,967	1,600	21,573	3,866
Long-term borrowings	56,214	66,049	189,805	178,048
Total interest expense	199,579	138,337	572,260	365,088
Net interest income	1,029,890	1,029,038	3,121,431	3,013,342
Provision for credit losses	45,000	16,000	122,000	94,000
Net interest income after provision for credit losses	984,890	1,013,038	2,999,431	2,919,342
Other income
Brokerage services income	12,077	12,267	37,031	38,288
Trading account and foreign exchange gains	16,072	6,073	45,327	15,965
Gain (loss) on bank investment securities	3,737	(3,415)	24,489	(10,520)
Other revenues from operations	103,882	113,769	351,082	340,351
Total other income	527,779	459,294	1,540,639	1,375,404
Other expense
Salaries and employee benefits	476,780	431,371	1,431,717	1,313,336
Equipment and net occupancy	82,690	77,481	241,187	225,309
Outside data processing and software	60,360	50,678	168,011	148,819
FDIC assessments	9,906	18,849	29,104	58,689
Advertising and marketing	22,088	21,784	66,409	59,800
Printing, postage and supplies	10,201	8,843	30,380	26,881
Amortization of core deposit and other intangible assets	5,088	6,143	15,185	19,163
Other costs of operations	210,506	160,830	663,006	633,903
Total other expense	877,619	775,979	2,644,999	2,485,900
Income before taxes	635,050	696,353	1,895,071	1,808,846
Income taxes	154,969	170,262	458,988	436,985
Net income	480,081	526,091	1,436,083	1,371,861
Net income available to common shareholders
Basic	461,410	505,363	1,376,128	1,310,697
Diluted	$ 461,410	$ 505,365	$ 1,376,129	$ 1,310,703
Net income per common share
Basic	$ 3.47	$ 3.54	$ 10.16	$ 9.01
Diluted	$ 3.47	$ 3.53	$ 10.16	$ 9.00
Average common shares outstanding
Basic	132,965	142,822	135,411	145,424
Diluted	132,999	142,976	135,443	145,605
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 137,004	$ 88,408	$ 339,636	$ 268,213
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	111,092	108,647	321,991	320,546
Trust Income [Member]
Other income
Revenue from contract with customer	$ 143,915	$ 133,545	$ 421,083	$ 402,561