Consolidated Statements Of Cash Flows - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES:
Net income		$ 327,454	$ 224,917
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		30,438	32,590
Provision for depreciation and amortization		28,824	29,521
Amortization of investment security premiums, net		18,758	28,173
Investment securities gains (losses), net	[1]	(6,641)	2,158
Net gains on sales of loans held for sale		(4,770)	(6,200)
Origination of loans held for sale		(149,397)	(162,552)
Proceeds from sales and repayments of held for sale		156,637	164,588
Net (increase) decrease in trading securities		(4,886)	7,234
Stock-based compensation		9,555	9,149
(Increase) decrease in interest receivable		(5,021)	(3,757)
Increase (decrease) in interest payable		689	(223)
Increase (decrease) in income taxes payable		30,107	201
Other changes, net		14,964	8,511
Net cash provided by (used in) operating activities		446,711	334,310
INVESTING ACTIVITIES:
Proceeds from sales of investment securities	[1]	193,047	369,036
Proceeds from maturities/pay downs of investment securities	[1]	1,222,998	1,384,993
Purchases of investment securities	[1]	(1,520,235)	(1,072,782)
Net (increase) decrease in loans		(3,588)	(364,765)
Payments for Securities Purchased under Agreements to Resell		(100,000)	(75,000)
Proceeds from Securities Purchased under Agreements to Resell		100,000	100,000
Purchases of land, buildings and equipment		(21,358)	(22,853)
Sales of land, buildings and equipment		2,342	2,570
Net cash provided by (used in) investing activities		(126,794)	321,199
FINANCING ACTIVITIES:
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits		(177,368)	(12,490)
Net increase (decrease) in time open and C.D.'s		(94,906)	(424,462)
Net increase (decrease) in federal funds purchased and short-term securities sold under agreements to repurchase		354,979	(314,921)
Repayment of long-term borrowings		(224)	(218)
Proceeds from Short-term Debt		0	722
Purchases of treasury stock		(39,575)	(11,320)
Issuance of stock under equity compensation plans		(10)	(7)
Cash dividends paid on common stock		(75,261)	(68,722)
Cash dividends paid on preferred stock		(6,750)	(6,750)
Net cash provided by (used in) financing activities		(39,115)	(838,168)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect		280,802	(182,659)
Cash, cash equivalents and restricted cash at beginning of year		524,352	782,435
Cash, cash equivalents and restricted cash at September 30		805,154	599,776
Supplemental Cash Flow Information:
Income tax payments, net		46,122	87,449
Interest paid on deposits and borrowings		44,074	32,387
Loans transferred to foreclosed real estate		$ 1,312	$ 1,166

[1] Available for sale debt securities, equity securities, and other securities