Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Assets
Cash and due from banks	$ 155,135	$ 218,276	$ 165,093
Money market and other interest-earning investments	61,690	45,784	97,953
Total cash and cash equivalents	216,825	264,060	263,046
Trading securities-at fair value	3,331	3,097	2,918
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	2,659,084	2,500,784	2,208,262
Investment securities-held-to-maturity, at amortized cost (fair value $419,326, $433,201 and $493,704 respectively)	401,066	402,828	463,935
Federal Home Loan Bank stock, at cost	40,584	37,927	30,835
Residential loans held for sale, at fair value	13,572	12,591	4,366
Finance leases held for sale	11,553
Commercial	1,397,882	1,336,820	1,205,532
Commercial real estate	1,197,997	1,255,883	1,042,581
Residential real estate	1,399,688	1,324,703	1,122,800
Consumer credit, net of unearned income	892,078	906,855	855,386
Covered loans, net of discount	288,577	372,333	489,331
Total loans	5,176,222	5,196,594	4,715,630
Allowance for loan losses	(43,890)	(49,047)	(50,424)
Allowance for loan losses-covered loans	(5,428)	(5,716)	(4,336)
Net loans	5,126,904	5,141,831	4,660,870
FDIC indemnification asset	100,391	116,624	136,994
Premises and equipment, net	91,445	89,868	71,823
Accrued interest receivable	48,516	46,979	44,163
Goodwill	339,382	338,820	253,177
Other intangible assets	24,993	29,220	30,205
Company-owned life insurance	273,887	270,629	251,676
Assets held for sale	9,275	15,047	12,784
Other real estate owned and repossessed personal property	7,739	11,179	10,765
Other real estate owned-covered	23,131	26,137	22,170
Other assets	249,393	236,002	221,567
Total assets	9,641,071	9,543,623	8,689,556
Deposits:
Noninterest-bearing demand	1,881,440	2,007,770	1,847,904
Interest-bearing:
NOW	1,652,816	1,827,665	1,603,669
Savings	1,900,148	1,869,377	1,683,777
Money market	283,686	292,860	283,092
Time	1,122,003	1,281,281	1,251,831
Total deposits	6,840,093	7,278,953	6,670,273
Short-term borrowings	530,381	589,815	346,000
Other borrowings	884,347	237,493	273,714
Accrued expenses and other liabilities	219,272	242,797	325,842
Total liabilities	8,474,093	8,349,058	7,615,829
Shareholders' Equity
Preferred stock, series A, 1,000 shares authorized, no shares issued or outstanding
Common stock, $1 stated value, 150,000 shares authorized, 100,881, 101,179 and 94,687 shares issued and outstanding, respectively	100,881	101,179	94,687
Capital surplus	912,391	916,918	835,028
Retained earnings	178,727	146,667	121,670
Accumulated other comprehensive income (loss), net of tax	(25,021)	29,801	22,342
Total shareholders' equity	1,166,978	1,194,565	1,073,727
Total liabilities and shareholders' equity	9,641,071	9,543,623	8,689,556
U.S. Treasury [Member]
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	14,366	11,841	15,598
U.S. Government-Sponsored Entities and Agencies [Member]
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	374,956	517,325	347,289
Mortgage-Backed Securities [Member]
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	1,412,869	1,193,984	1,214,689
States and Political Subdivisions [Member]
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	643,887	577,324	462,065
Other Securities [Member]
Investment securities-available-for-sale, at fair value
Total investment securities - available-for-sale	$ 213,006	$ 200,310	$ 168,621