Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Assets
Cash and due from banks	$ 197,446	$ 190,606	$ 133,939
Money market and other interest-earning investments	17,078	16,117	19,964
Total cash and cash equivalents	214,524	206,723	153,903
Trading securities - at fair value	3,681	3,566	3,217
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	2,369,064	2,372,201	2,848,410
Investment securities - held-to-maturity, at amortized cost (fair value $812,914, $780,758 and $423,325 respectively)	779,294	762,734	392,379
Federal Home Loan Bank stock, at cost	40,584	40,584	37,927
Residential loans held for sale, at fair value	6,169	7,705	14,583
Loans:
Commercial	1,367,486	1,373,415	1,315,136
Commercial real estate	1,156,593	1,160,890	1,230,310
Residential real estate	1,356,233	1,359,569	1,352,679
Consumer credit, net of unearned income	997,808	971,258	887,520
Covered loans, net of discount	194,161	217,832	326,397
Total loans	5,072,281	5,082,964	5,112,042
Allowance for loan losses	(41,539)	(41,741)	(47,313)
Allowance for loan losses - covered loans	(6,014)	(5,404)	(6,168)
Net loans	5,024,728	5,035,819	5,058,561
FDIC indemnification asset	65,699	88,513	109,861
Premises and equipment, net	108,866	108,306	89,847
Accrued interest receivable	48,764	50,205	46,575
Goodwill	352,729	352,729	338,820
Other intangible assets	24,120	25,957	26,695
Company-owned life insurance	276,956	275,121	272,273
Assets held for sale	9,043	9,056	10,353
Other real estate owned and repossessed personal property	7,629	7,562	9,103
Other real estate owned - covered	12,918	13,670	26,114
Other assets	200,012	221,293	235,070
Total assets	9,544,780	9,581,744	9,673,691
Deposits:
Noninterest-bearing demand	2,047,664	2,026,490	1,973,265
Interest-bearing:
NOW	1,789,167	1,775,938	1,691,231
Savings	2,014,574	1,941,652	1,916,880
Money market	445,953	448,848	294,744
Time	960,804	1,017,975	1,190,199
Total deposits	7,258,162	7,210,903	7,066,319
Short-term borrowings	410,128	462,332	644,021
Other borrowings	506,782	556,388	536,798
Accrued expenses and other liabilities	184,471	189,481	226,888
Total liabilities	8,359,543	8,419,104	8,474,026
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, 100,084, 99,859 and 101,367 shares issued and outstanding, respectively	100,084	99,859	101,367
Capital surplus	900,665	900,254	917,064
Retained earnings	222,418	206,993	160,416
Accumulated other comprehensive income (loss), net of tax	(37,930)	(44,466)	20,818
Total shareholders' equity	1,185,237	1,162,640	1,199,665
Total liabilities and shareholders' equity	9,544,780	9,581,744	9,673,691
U.S. Treasury [Member]
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	15,697	13,113	11,582
U.S. Government-Sponsored Entities and Agencies [Member]
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	490,080	435,588	404,740
Mortgage-Backed Securities [Member]
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	1,246,408	1,306,670	1,548,011
States and Political Subdivisions [Member]
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	251,839	268,795	665,339
Other Securities [Member]
Investment securities - available-for-sale, at fair value
Total investment securities - available-for-sale	$ 365,040	$ 348,035	$ 218,738