Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Assets
Cash and due from banks	$ 165,093	$ 191,626	$ 139,821
Money market and other interest-earning investments	97,953	31,246	195,796
Total cash and cash equivalents	263,046	222,872	335,617
Trading securities - at fair value	2,918	2,816	2,916
Investment securities - available-for-sale, at fair value
Available-for-sale securities	2,208,262
Total investment securities - available-for-sale	2,208,262	2,071,276	2,202,855
Investment securities - held-to-maturity, at amortized cost (fair value $493,704, $507,699 and $574,174 respectively)	463,935	484,590	567,708
Federal Home Loan Bank stock, at cost	30,835	30,835	19,673
Residential loans held for sale, at fair value	4,366	4,528	6,104
Loans:
Commercial	1,205,532	1,216,654	1,269,607
Commercial real estate	1,042,581	1,067,370	1,170,401
Residential real estate	1,122,800	995,458	795,442
Consumer credit, net of unearned income	855,386	861,361	881,891
Covered loans, net of discount	489,331	626,360	0
Total loans	4,715,630	4,767,203	4,117,341
Allowance for loan losses	(50,424)	(57,117)	(70,189)
Allowance for loan losses - covered loans	(4,336)	(943)	0
Net loans	4,660,870	4,709,143	4,047,152
FDIC indemnification asset	127,717	147,566	0
Premises and equipment, net	71,823	71,870	65,915
Accrued interest receivable	44,163	44,801	42,600
Goodwill	253,177	253,177	236,313
Other intangible assets	30,205	33,624	34,114
Company-owned life insurance	251,676	248,693	245,841
Assets held for sale	12,784	16,861	0
Other real estate owned and repossessed personal property	10,765	7,119	9,875
Other real estate owned - covered	22,170	30,443	0
Other assets	230,844	229,469	202,165
Total assets	8,689,556	8,609,683	8,018,848
Deposits [Abstract]
Noninterest-bearing demand	1,847,904	1,728,546	1,504,632
Interest-bearing:
NOW	1,603,669	1,569,084	1,332,961
Savings	1,683,777	1,570,422	1,304,172
Money market	283,092	295,847	315,344
Time	1,251,831	1,447,664	1,557,978
Total deposits	6,670,273	6,611,563	6,015,087
Short-term borrowings	346,000	424,849	305,205
Other borrowings	273,714	290,774	440,470
Accrued expenses and other liabilities	325,842	248,941	249,812
Total liabilities	7,615,829	7,576,127	7,010,574
Shareholders' Equity
Preferred stock, series A, 1,000 shares authorized, no shares issued or outstanding	0	0	0
Common stock, $1 stated value, 150,000 shares authorized, 94,687, 94,654 and 94,752 shares issued and outstanding, respectively	94,687	94,654	94,752
Capital surplus	835,028	834,033	832,942
Retained earnings	121,670	89,865	64,178
Accumulated other comprehensive income, net of tax	22,342	15,004	16,402
Total shareholders' equity	1,073,727	1,033,556	1,008,274
Total liabilities and shareholders' equity	8,689,556	8,609,683	8,018,848
U.S. Treasury [Member]
Investment securities - available-for-sale, at fair value
Available-for-sale securities	15,598	65,769	62,746
U.S. Government-Sponsored Entities And Agencies [Member]
Investment securities - available-for-sale, at fair value
Available-for-sale securities	347,289	173,185	387,211
Mortgage-Backed Securities [Member]
Investment securities - available-for-sale, at fair value
Available-for-sale securities	1,214,689	1,268,155	1,207,624
States And Political Subdivisions [Member]
Investment securities - available-for-sale, at fair value
Available-for-sale securities	462,065	402,844	368,421
Other Securities [Member]
Investment securities - available-for-sale, at fair value
Available-for-sale securities	$ 168,621	$ 161,323	$ 176,853