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	$ 217,535	$ 208,764	$ 179,034
Adjustments to reconcile net income to net cash from operating activities:
Provision for loan losses	27,445	43,611	65,392
Deferred tax expense (benefit)	8,167	4,644	(9,854)
Accretion of loan discounts	(12,974)	(11,336)	(13,974)
Securities premium amortization (discount accretion), net	11,441	8,065	3,108
Net (gain) loss on securities transactions	(6,414)	(6)	1,260
Depreciation and amortization	37,628	37,588	36,459
Net (gain) loss on sale of loans held for sale and other assets	4,677	5,929	2,584
Stock-based compensation	15,963	14,925	12,645
Net tax benefit (deficiency) from stock-based compensation	(106)	(264)	815
Excess tax benefits from stock-based compensation	(422)	(683)	(681)
Earnings on life insurance policies	(4,045)	(4,517)	(4,858)
Net change in:
Trading account securities	1,492	1,025	(1,574)
Student loans held for sale		24,029	4,829
Accrued interest receivable and other assets	(15,502)	69,830	68,162
Accrued interest payable and other liabilities	(10,516)	22,929	(69,418)
Net cash from operating activities	274,369	424,533	273,929
Securities held to maturity:
Purchases	(83,184)	(277,998)	(1,000)
Maturities, calls and principal repayments	665	708	1,832
Securities available for sale:
Purchases	(8,752,573)	(11,194,766)	(12,389,403)
Sales	5,587,391	9,997,994	206,477
Maturities, calls and principal repayments	729,678	893,702	10,930,488
Net change in loans	70,200	176,599	403,865
Net cash paid in acquisitions	(650)		(1,205)
Proceeds from sales of premises and equipment	1,339	1,063	715
Purchases of premises and equipment	(26,719)	(16,826)	(78,262)
Benefits received on life insurance policies			650
Proceeds from sales of repossessed properties	18,562	19,705	6,460
Net cash from investing activities	(2,455,291)	(399,819)	(919,383)
Financing Activities:
Net change in deposits	2,277,406	1,166,032	1,804,373
Net change in short-term borrowings	246,529	(6,375)	(591,231)
Proceeds from long-term borrowings			230,000
Principal payments on long-term borrowings	(150,019)	(18,889)	(230,015)
Proceeds from stock option exercises	7,438	38,807	16,226
Excess tax benefits from stock-based compensation	422	683	681
Purchase of treasury stock	(2,029)	(986)	(800)
Common stock/treasury stock sold to the 401(k) stock purchase plan		3,539	2,498
Cash dividends paid	(112,210)	(108,027)	(102,130)
Net cash from financing activities	2,267,537	1,074,784	1,129,602
Net change in cash and cash equivalents	86,615	1,099,498	484,148
Cash and cash equivalents at beginning of year	2,820,977	1,721,479	1,237,331
Cash and cash equivalents at end of year	$ 2,907,592	$ 2,820,977	$ 1,721,479