Consolidated Statements Of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES:
Net income		$ 71,702	$ 65,522
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		11,128	9,439
Provision for depreciation and amortization		10,019	10,146
Amortization of investment security premiums, net		9,231	11,188
Investment securities gains (losses), net	[1]	772	995
Net gains on sales of loans held for sale		(866)	(969)
Origination of loans held for sale		(34,716)	(24,009)
Proceeds from sales and repayments of held for sale		34,446	22,666
Net (increase) decrease in trading securities, excluding unsettled transactions		7,763	76,143
Stock-based compensation		3,135	3,411
(Increase) decrease in interest receivable		(686)	(473)
Increase (decrease) in interest payable		39	280
Increase (decrease) in income taxes payable		21,156	26,133
Other changes, net		8,182	(3,352)
Net cash provided by (used in) operating activities		141,305	197,120
INVESTING ACTIVITIES:
Proceeds from sales of investment securities	[1]	98	94
Proceeds from maturities/pay downs of investment securities	[1]	483,090	542,059
Purchases of investment securities	[1]	(482,642)	(180,774)
Net (increase) decrease in loans		(169,185)	(320,987)
Repayments of long-term securities purchased under agreements to resell		0	50,000
Purchases of land, buildings and equipment		(5,456)	(7,389)
Sales of land, buildings and equipment		717	520
Net cash provided by (used in) investing activities		(173,378)	83,523
FINANCING ACTIVITIES:
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits		49,469	421,286
Net increase (decrease) in time open and C.D.'s		174,052	418,177
Net increase (decrease) in federal funds purchased and short-term securities sold under agreements to repurchase		(402,756)	(1,006,164)
Repayment of long-term borrowings		(74)	(12)
Purchases of treasury stock		(7,284)	(36,432)
Issuance of stock under equity compensation plans		(6)	0
Cash dividends paid on common stock		(22,913)	(21,760)
Cash dividends paid on preferred stock		(2,250)	(2,250)
Net cash provided by (used in) financing activities		(211,762)	(227,155)
Increase (decrease) in cash and cash equivalents		(243,835)	53,488
Cash and cash equivalents at beginning of year		782,435	502,719
Cash and cash equivalents at end of period		538,600	556,207
Supplemental Cash Flow Information:
Income tax payments, net		2,850	2,658
Interest paid on deposits and borrowings		9,685	8,073
Loans transferred to foreclosed real estate		134	471
Transfer of loans held for investment to held for sale		$ 0	$ 50,360

[1] Available for sale and non-marketable securities