Consolidated Statement of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest income
Loans and leases, including fees	$ 3,485,050	$ 2,778,151	$ 2,596,586
Investment securities
Fully taxable	361,494	372,162	340,391
Exempt from federal taxes	2,606	4,263	5,356
Deposits at banks	45,516	15,252	13,361
Other	1,205	1,016	1,183
Total interest income	3,895,871	3,170,844	2,956,877
Interest expense
Savings and interest-checking deposits	87,704	46,140	46,869
Time deposits	102,841	27,059	15,515
Deposits at Cayman Islands office	797	615	699
Short-term borrowings	3,625	1,677	101
Long-term borrowings	231,017	252,766	217,247
Total interest expense	425,984	328,257	280,431
Net interest income	3,469,887	2,842,587	2,676,446
Provision for credit losses	190,000	170,000	124,000
Net interest income after provision for credit losses	3,279,887	2,672,587	2,552,446
Other income
Mortgage banking revenues	373,697	375,738	362,912
Service charges on deposit accounts	419,102	420,608	427,956
Trust income	472,184	470,640	508,258
Brokerage services income	63,423	64,770	67,212
Trading account and foreign exchange gains	41,126	30,577	29,874
Gain (loss) on bank investment securities	30,314	(130)
Other revenues from operations	426,150	462,834	383,061
Total other income	1,825,996	1,825,037	1,779,273
Other expense
Salaries and employee benefits	1,623,600	1,549,530	1,404,950
Equipment and net occupancy	295,141	272,539	269,299
Outside data processing and software	172,389	164,133	151,568
FDIC assessments	105,045	52,113	55,531
Advertising and marketing	87,137	59,227	47,111
Printing, postage and supplies	39,546	38,491	38,201
Amortization of core deposit and other intangible assets	42,613	26,424	33,824
Other costs of operations	682,014	660,475	688,990
Total other expense	3,047,485	2,822,932	2,689,474
Income before taxes	2,058,398	1,674,692	1,642,245
Income taxes	743,284	595,025	575,999
Net income	1,315,114	1,079,667	1,066,246
Net income available to common shareholders
Basic	1,223,459	987,689	978,531
Diluted	$ 1,223,481	$ 987,724	$ 978,581
Net income per common share
Basic	$ 7.80	$ 7.22	$ 7.47
Diluted	$ 7.78	$ 7.18	$ 7.42