Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Assets:
Cash and due from banks	$ 637,042	$ 574,039	$ 571,332
Interest-bearing deposits	2,098,682	2,314,251	3,885,202
Federal funds sold and resell agreements	16,452	19,302	30,827
Total cash and cash equivalents	2,752,176	2,907,592	4,487,361
Securities held to maturity, at amortized cost	364,997	365,996	366,267
Securities available for sale, at estimated fair value	8,717,645	7,789,700	5,339,812
Trading account securities	14,823	13,609	15,823
Loans, net of unearned discounts	8,811,040	7,995,129	8,089,577
Less: Allowance for loan losses	(105,401)	(110,147)	(115,433)
Net loans	8,705,639	7,884,982	7,974,144
Premises and equipment, net	317,197	319,042	321,517
Goodwill	535,509	528,072	528,072
Other intangible assets, net	9,066	10,604	11,656
Cash surrender value of life insurance policies	137,009	133,967	132,899
Accrued interest receivable and other assets	293,480	363,681	312,091
Total assets	21,847,541	20,317,245	19,489,642
Liabilities:
Non-interest-bearing demand deposits	7,720,930	6,672,555	6,541,239
Interest-bearing deposits	10,524,267	10,084,193	9,522,634
Total deposits	18,245,197	16,756,748	16,063,873
Federal funds purchased and repurchase agreements	601,204	722,202	658,246
Junior subordinated deferrable interest debentures	123,712	123,712	123,712
Other long-term borrowings	100,012	100,026	100,031
Accrued interest payable and other liabilities	358,799	331,020	296,904
Total liabilities	19,428,924	18,033,708	17,242,766
Shareholders' Equity:
Preferred stock, par value $0.01 per share; 10,000,000 shares authorized; none issued
Common stock, par value $0.01 per share; 210,000,000 shares authorized; 61,461,924, shares issued at September 30, 2012, 61,271,603 shares issued at December 31, 2011 and 61,271,603 shares issued at September 30, 2011	615	613	613
Additional paid-in capital	698,038	680,803	676,079
Retained earnings	1,445,241	1,354,759	1,327,587
Accumulated other comprehensive income, net of tax	274,723	247,734	244,053
Treasury stock, 7,640 shares at December 31, 2011 and 26,359 shares at September 30, 2011, at cost		(372)	(1,456)
Total shareholders' equity	2,418,617	2,283,537	2,246,876
Total liabilities and shareholders' equity	$ 21,847,541	$ 20,317,245	$ 19,489,642