Consolidated Statements Of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES:
Net income		$ 97,055	$ 102,061
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		12,463	10,396
Provision for depreciation and amortization		9,966	9,620
Amortization of investment security premiums, net		9,998	7,233
Investment securities gains (losses), net	[1]	925	(5,410)
Net gains on sales of loans held for sale		(1,929)	(1,147)
Origination of loans held for sale		(46,454)	(44,066)
Proceeds from sales and repayments of held for sale		48,506	49,255
Net (increase) decrease in trading securities		4,632	(18,543)
Stock-based compensation		3,480	3,290
(Increase) decrease in interest receivable		(1,568)	744
Increase (decrease) in interest payable		2,708	(732)
Increase (decrease) in income taxes payable		20,479	22,076
Other changes, net		(18,080)	9,212
Net cash provided by (used in) operating activities		142,181	143,989
INVESTING ACTIVITIES:
Proceeds from sales of investment securities	[1]	150,756	148,652
Proceeds from maturities/pay downs of investment securities	[1]	252,824	358,690
Purchases of investment securities	[1]	(432,645)	(298,554)
Net (increase) decrease in loans		7,758	78,838
Purchases of land, buildings and equipment		(11,283)	(4,982)
Sales of land, buildings and equipment		1,268	718
Net cash provided by (used in) investing activities		(31,322)	283,362
FINANCING ACTIVITIES:
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits		(620,589)	54,986
Net increase (decrease) in time open and C.D.'s		218,161	(9,961)
Net increase (decrease) in federal funds purchased and short-term securities sold under agreements to repurchase		(233,638)	(374,809)
Repayment of long-term borrowings		(54)	(74)
Proceeds from (Repayments of) Short-term Debt		(6,736)	7,530
Purchases of treasury stock		(39,699)	(17,067)
Issuance of stock under equity compensation plans		(4)	(6)
Cash dividends paid on common stock		(28,858)	(25,106)
Cash dividends paid on preferred stock		(2,250)	(2,250)
Net cash provided by (used in) financing activities		(713,667)	(366,757)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect		(602,808)	60,594
Cash, cash equivalents and restricted cash at beginning of year		1,209,240	524,352
Cash, cash equivalents and restricted cash at March 31		606,432	584,946
Supplemental Cash Flow Information:
Income tax payments, net		1,350	147
Interest paid on deposits and borrowings		21,668	13,835
Loans transferred to foreclosed real estate		$ 54	$ 1,028

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