Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES
Net income	$ 259,623	$ 221,875	$ 168,375
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	51,515	100,000	160,697
Provision for depreciation and amortization	46,743	48,924	51,514
Amortization of investment security premiums, net	18,972	21,635	2,348
Deferred income tax benefit	(2,836)	(9,085)	(7,310)
Investment securities (gains) losses, net	(10,812)	1,785	7,195
Gain on sale of held to maturity student loans		(6,914)
Net gains on sales of loans held for sale	(2,040)	(10,402)	(12,201)
Proceeds from sales of loans held for sale	87,732	635,743	577,726
Originations of loans held for sale	(52,995)	(344,360)	(545,380)
Net (increase) decrease in trading securities	2,354	(928)	(14,014)
Stock-based compensation	4,731	6,021	6,642
(Increase) decrease in interest receivable	(2,010)	12,041	2,943
Decrease in interest payable	(4,598)	(9,462)	(18,574)
Increase (decrease) in income taxes payable	14,519	2,714	(3,067)
Net tax benefit related to equity compensation plans	(1,065)	(1,178)	(557)
Prepayment of FDIC insurance premiums			(63,739)
Other changes, net	(2,472)	2,768	(17,310)
Net cash provided by operating activities	407,361	671,177	295,288
INVESTING ACTIVITIES
Net cash and cash equivalents paid in dispositions			(3,494)
Proceeds from sales of available for sale securities	19,833	78,640	207,852
Proceeds from maturities/pay downs of available for sale securities	2,562,551	2,308,323	1,332,347
Purchases of available for sale securities	(4,517,463)	(3,217,600)	(4,078,962)
Net decrease in loans	168,983	644,314	999,086
Long-term securities purchased under agreements to resell	(500,000)	(450,000)
Repayments of long-term securities purchased under agreements to resell	100,000
Purchases of land, buildings and equipment	(21,332)	(18,528)	(29,247)
Sales of land, buildings and equipment	2,593	397	151
Net cash used in investing activities	(2,184,835)	(654,454)	(1,572,267)
FINANCING ACTIVITIES
Net increase in non-interest bearing, savings, interest checking and money market deposits	1,981,201	1,300,555	2,041,513
Net decrease in time open and C.D.'s	(255,769)	(469,557)	(693,941)
Long-term securities sold under agreements to repurchase		400,000
Repayment of long-term securities sold under agreements to repurchase		(500,000)
Net increase (decrease) in short-term federal funds purchased and securities sold under agreements to repurchase	273,254	(20,364)	76,654
Additional other long-term borrowings			100,000
Repayment of other long-term borrowings	(456)	(623,789)	(311,719)
Net decrease in other short-term borrowings			(800,000)
Purchases of treasury stock	(101,154)	(40,984)	(528)
Issuance of stock under open market stock sale program, stock purchase and equity compensation plans	15,349	11,310	103,641
Net tax benefit related to equity compensation plans	1,065	1,178	557
Cash dividends paid on common stock	(79,140)	(78,231)	(74,720)
Net cash provided by (used in) financing activities	1,834,350	(19,882)	441,457
Increase (decrease) in cash and cash equivalents	56,876	(3,159)	(835,522)
Cash and cash equivalents at beginning of year	460,675	463,834	1,299,356
Cash and cash equivalents at end of year	517,551	460,675	463,834
Income tax payments, net	106,653	100,610	82,900
Interest paid on deposits and borrowings	56,499	93,008	172,608
Loans transferred to foreclosed real estate	$ 22,957	$ 16,440	$ 12,857