Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OPERATING ACTIVITIES:
Net income	$ 60,808	$ 66,814
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	3,285	8,165
Provision for depreciation and amortization	10,424	11,021
Amortization of investment security premiums, net	12,539	11,987
Investment securities gains, net	2,165	(4,040)
Net gains on sales of loans held for sale	0	(358)
Proceeds from sales of loans held for sale	0	21,699
Net increase in trading securities	9,609	(11,300)
Stock-based compensation	1,223	1,407
(Increase) decrease in interest receivable	(5)	3,825
Decrease in interest payable	246	114
Increase in income taxes payable	26,894	23,496
Net tax benefit related to equity compensation plans	(181)	(649)
Other changes, net	(28,936)	(12,036)
Net cash provided by operating activities	98,071	120,145
INVESTING ACTIVITIES:
Proceeds from sales of investment securities	52	6,986
Proceeds from maturities/pay downs of investment securities	674,270	643,378
Purchases of investment securities	(934,142)	(558,651)
Net (increase) decrease in loans	(159,087)	(81,658)
Long-term securities purchased under agreements to resell	(50,000)	0
Repayments of long-term securities purchased under agreements to resell	50,000	0
Purchases of land, buildings and equipment	(5,867)	(5,393)
Sales of land, buildings and equipment	404	701
Net cash used in investing activities	(424,370)	5,363
FINANCING ACTIVITIES:
Net increase in non-interest bearing, savings, interest checking and money market deposits	(138,419)	(84,876)
Net decrease in time open and C.D.'s	310,948	35,703
Net increase in short-term federal funds purchased and securities sold under agreements to repurchase	43,308	(133,093)
Repayment of long-term borrowings	(927)	(297)
Purchases of treasury stock	(29,993)	(31,600)
Issuance of stock under stock purchase and equity compensation plans	2,606	5,954
Net tax benefit related to equity compensation plans	181	649
Cash dividends paid on common stock	(20,435)	(1,074)
Net cash provided by financing activities	167,269	(208,634)
Increase (decrease) in cash and cash equivalents	(159,030)	(83,126)
Cash and cash equivalents at beginning of year	779,825	517,551
Cash and cash equivalents at September 30	620,795	434,425
Supplemental Cash Flow Information:
Income tax payments, net	2,031	9,271
Interest paid on deposits and borrowings	8,156	10,115
Loans transferred to foreclosed real estate	3,925	1,311
Cash dividends payable on common stock at end of period	$ 0	$ 19,364