Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Assets:
Cash and due from banks	$ 609,211	$ 574,039	$ 575,464
Interest-bearing deposits	1,673,538	2,314,251	2,836,046
Federal funds sold and resell agreements	12,502	19,302	9,051
Total cash and cash equivalents	2,295,251	2,907,592	3,420,561
Securities held to maturity, at amortized cost	365,356	365,996	349,997
Securities available for sale, at estimated fair value	8,475,767	7,789,700	5,432,354
Trading account securities	16,563	13,609	14,517
Loans, net of unearned discounts	8,489,763	7,995,129	8,068,212
Less: Allowance for loan losses	(105,648)	(110,147)	(122,741)
Net loans	8,384,115	7,884,982	7,945,471
Premises and equipment, net	319,904	319,042	316,165
Goodwill	535,560	528,072	528,072
Other intangible assets, net	10,039	10,604	12,764
Cash surrender value of life insurance policies	136,041	133,967	131,883
Accrued interest receivable and other assets	327,630	363,681	326,602
Total assets	20,866,226	20,317,245	18,478,386
Liabilities:
Non-interest-bearing demand deposits	7,136,674	6,672,555	5,818,692
Interest-bearing deposits	10,140,443	10,084,193	9,285,439
Total deposits	17,277,117	16,756,748	15,104,131
Federal funds purchased and repurchase agreements	656,025	722,202	574,132
Junior subordinated deferrable interest debentures	123,712	123,712	123,712
Other long-term borrowings	100,017	100,026	250,036
Accrued interest payable and other liabilities	346,744	331,020	249,730
Total liabilities	18,503,615	18,033,708	16,301,741
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; 61,404,274, shares issued at June 30, 2012, 61,271,603 shares issued at December 31, 2011 and 61,271,603 shares issued at June 30, 2011	614	613	613
Additional paid-in capital	692,625	680,803	673,620
Retained earnings	1,416,097	1,354,759	1,301,279
Accumulated other comprehensive income, net of tax	253,275	247,734	202,589
Treasury stock, 7,640 shares at December 31, 2011 and 26,359 shares at June 30, 2011, at cost		(372)	(1,456)
Total shareholders' equity	2,362,611	2,283,537	2,176,645
Total liabilities and shareholders' equity	$ 20,866,226	$ 20,317,245	$ 18,478,386