Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income	$ 438,214	$ 319,900	$ 276,854
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	42,694	45,244	36,318
Provision for depreciation and amortization	38,679	39,732	40,929
Amortization of investment security premiums, net	26,224	35,423	31,493
Deferred income tax (benefit) expense	5,336	13,617	(2,059)
Investment securities (gains) losses, net	488	(25,051)	53
Net gains on sales of loans held for sale	(6,370)	(8,008)	(5,850)
Proceeds from sales of loans held for sale	208,431	215,373	160,875
Origination Of Loans Held For Sale	(203,775)	(216,064)	(163,469)
Net (increase) decrease in trading securities	(14,277)	7,585	73,780
Stock-based compensation	12,841	12,105	11,525
(Increase) decrease in interest receivable	(4,258)	(4,459)	(3,642)
Increase (decrease) in interest payable	2,137	38	1,107
Increase (decrease) in income taxes payable	12,288	(27,685)	4,509
Donation of securities	0	32,036	0
Other changes, net	(5,992)	(13,259)	(7,460)
Net cash provided by (used in) operating activities	552,660	426,527	454,963
INVESTING ACTIVITIES
Proceeds from sales of available for sale securities	708,864	792,380	24,380
Proceeds from maturities/pay downs of available for sale securities	1,510,985	1,899,640	2,032,397
Purchases of available for sale securities	(2,090,333)	(1,853,817)	(1,988,101)
Net (increase) decrease in loans	(200,673)	(614,849)	(1,009,523)
Repayments of long-term securities purchased under agreements to resell	(100,000)	(75,000)	(250,000)
Proceeds from Securities Purchased under Agreements to Resell	100,000	100,000	400,000
Purchases of land, buildings and equipment	(33,294)	(30,824)	(24,478)
Sales of land, buildings and equipment	13,427	3,190	10,112
Net cash provided by (used in) investing activities	(91,024)	220,720	(805,213)
FINANCING ACTIVITIES
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits	60,278	(15,036)	782,846
Net increase (decrease) in time open and C.D.’s	(108,742)	(474,044)	243,199
Net increase (decrease) in short-term federal funds purchased and securities sold under agreements to repurchase	449,251	(216,767)	(239,647)
Increase (decrease) in other borrowings	6,944	(100,291)	(1,769)
Purchases of treasury stock	(75,231)	(17,771)	(39,381)
Issuance of stock under equity compensation plans	(10)	(8)	(6)
Cash dividends paid on common stock	(100,238)	(91,619)	(87,070)
Cash dividends paid on preferred stock	(9,000)	(9,000)	(9,000)
Net cash provided by (used in) financing activities	223,252	(924,536)	649,172
Increase (decrease) in cash and cash equivalents	684,888	(277,289)	298,922
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning of Year	524,352	801,641	502,719
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, End of Year	1,209,240	524,352	801,641
Supplemental Cash Flow Information:
Income tax payments, net	84,172	120,744	119,596
Interest paid on deposits and borrowings	63,239	43,690	31,896
Real Estate Owned, Transfer to Real Estate Owned	1,551	2,063	1,122
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 0	$ 0	$ 42,688