Consolidated Statements Of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net income		$ 422,712	$ 438,214	$ 319,900
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		50,438	42,694	45,244
Provision for depreciation and amortization		41,145	38,679	39,732
Amortization of investment security premiums, net		27,631	26,224	35,423
Deferred income tax (benefit) expense		14,195	5,336	13,617
Investment securities (gains) losses, net	[1]	(3,626)	488	(25,051)
Net gains on sales of loans held for sale		(10,127)	(6,370)	(8,008)
Proceeds from sales of loans held for sale		259,153	208,431	215,373
Origination Of Loans Held For Sale		(244,976)	(203,775)	(216,064)
Net (increase) decrease in trading securities		3,863	(14,277)	7,585
Stock-based compensation		13,854	12,841	12,105
(Increase) decrease in interest receivable		3,316	(4,258)	(4,459)
Increase (decrease) in interest payable		5,586	2,137	38
Increase (decrease) in income taxes payable		14,465	12,288	(27,685)
Donation of securities		0	0	32,036
Gain on sale of Corporate Trust business		(11,472)	0	0
Other changes, net		(73,363)	(5,992)	(13,259)
Net cash provided by (used in) operating activities		512,794	552,660	426,527
INVESTING ACTIVITIES
Proceeds from sales of available for sale securities	[1]	413,203	708,864	792,380
Proceeds from maturities/pay downs of available for sale securities	[1]	1,558,244	1,510,985	1,899,640
Purchases of available for sale securities	[1]	(1,863,180)	(2,090,333)	(1,853,817)
Net (increase) decrease in loans		(647,890)	(200,673)	(614,849)
Repayments of long-term securities purchased under agreements to resell		(150,000)	(100,000)	(75,000)
Proceeds from Securities Purchased under Agreements to Resell		0	100,000	100,000
Purchases of land, buildings and equipment		(42,575)	(33,294)	(30,824)
Sales of land, buildings and equipment		2,033	13,427	3,190
Net cash provided by (used in) investing activities		(730,165)	(91,024)	220,720
FINANCING ACTIVITIES
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits		85,438	60,278	(15,036)
Net increase (decrease) in time open and C.D.’s		349,890	(108,742)	(474,044)
Net increase (decrease) in short-term federal funds purchased and securities sold under agreements to repurchase		(105,617)	449,251	(216,767)
Increase (decrease) in other borrowings		(6,394)	6,944	(100,291)
Purchases of treasury stock		(134,904)	(75,231)	(17,771)
Accelerated stock repurchase agreement		150,000	0	0
Issuance of stock under equity compensation plans		(8)	(10)	(8)
Cash dividends paid on common stock		(113,466)	(100,238)	(91,619)
Cash dividends paid on preferred stock		(9,000)	(9,000)	(9,000)
Net cash provided by (used in) financing activities		(84,061)	223,252	(924,536)
Increase (decrease) in cash and cash equivalents		(301,432)	684,888	(277,289)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning of Year		1,209,240	524,352	801,641
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, End of Year		907,808	1,209,240	524,352
Supplemental Cash Flow Information:
Income tax payments, net		76,168	84,172	120,744
Interest paid on deposits and borrowings		97,806	63,239	43,690
Loans transferred to foreclosed real estate		$ 581	$ 1,551	$ 2,063

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