Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest income
Loans and leases, including fees	$ 1,117,913	$ 979,969
Investment securities
Fully taxable	80,411	82,852
Exempt from federal taxes	95	248
Deposits at banks	27,407	18,677
Other	483	404
Total interest income	1,226,309	1,082,150
Interest expense
Savings and interest-checking deposits	76,138	40,527
Time deposits	21,081	10,936
Deposits at Cayman Islands office	4,738	381
Short-term borrowings	6,713	883
Long-term borrowings	67,579	53,906
Total interest expense	176,249	106,633
Net interest income	1,050,060	975,517
Provision for credit losses	22,000	43,000
Net interest income after provision for credit losses	1,028,060	932,517
Other income
Brokerage services income	12,476	13,392
Trading account and foreign exchange gains	10,802	4,637
Gain (loss) on bank investment securities	11,841	(9,431)
Other revenues from operations	134,437	126,302
Total other income	500,765	458,696
Other expense
Salaries and employee benefits	499,200	463,428
Equipment and net occupancy	79,347	74,797
Outside data processing and software	52,417	48,429
FDIC assessments	9,426	20,280
Advertising and marketing	20,275	16,248
Printing, postage and supplies	9,855	9,319
Amortization of core deposit and other intangible assets	5,020	6,632
Other costs of operations	218,808	294,211
Total other expense	894,348	933,344
Income before taxes	634,477	457,869
Income taxes	151,735	105,259
Net income	482,742	352,610
Net income available to common shareholders
Basic	462,086	332,748
Diluted	$ 462,086	$ 332,749
Net income per common share
Basic	$ 3.35	$ 2.24
Diluted	$ 3.35	$ 2.23
Average common shares outstanding
Basic	137,889	148,688
Diluted	137,920	148,905
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 95,311	$ 87,306
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	103,112	105,115
Trust Income [Member]
Other income
Revenue from contract with customer	$ 132,786	$ 131,375