Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Assets
Cash and due from banks	$ 178,985	$ 207,871	$ 215,806
Money market and other interest-earning investments	16,228	32,092	20,887
Total cash and cash equivalents	195,213	239,963	236,693
Trading securities - at fair value	3,995	3,881	3,726
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	2,572,521	2,627,831	2,513,117
Investment securities - held-to-maturity, at amortized cost (fair value $867,345, $903,935 and $899,007, respectively)	823,255	844,054	852,904
Federal Home Loan Bank/Federal Reserve stock, at cost	71,669	71,175	65,716
Loans held for sale ($20,287, $15,562, and $11,398, respectively at fair value)	217,667	213,490	11,398
Loans:
Commercial	1,775,954	1,629,600	1,498,833
Commercial real estate	1,767,341	1,711,110	1,354,700
Residential real estate	1,622,819	1,519,156	1,425,179
Consumer credit, net of unearned income	1,464,541	1,310,627	1,089,008
Covered loans, net of discount	135,407	147,708	171,148
Total loans	6,766,062	6,318,201	5,538,868
Allowance for loan losses	(48,479)	(44,297)	(42,494)
Allowance for loan losses - covered loans	(1,712)	(3,552)	(3,658)
Net loans	6,715,871	6,270,352	5,492,716
FDIC indemnification asset	16,475	20,603	51,431
Premises and equipment, net	131,336	135,892	118,014
Accrued interest receivable	66,605	60,966	54,630
Goodwill	588,464	530,845	408,474
Other intangible assets	40,996	38,694	30,799
Company-owned life insurance	337,802	325,617	299,509
Assets held for sale	9,886	9,127	9,043
Other real estate owned and repossessed personal property	9,388	7,241	6,729
Other real estate owned - covered	4,753	9,121	11,155
Other assets	269,924	238,699	221,879
Total assets	12,075,820	11,647,551	10,387,933
Deposits:
Noninterest-bearing demand	2,557,665	2,427,748	2,129,705
Interest-bearing:
NOW	2,213,862	2,176,879	1,912,183
Savings	2,352,916	2,222,557	2,100,173
Money market	602,287	574,462	428,013
Time	1,082,840	1,089,018	984,929
Total deposits	8,809,570	8,490,664	7,555,003
Short-term borrowings	530,377	551,309	467,578
Other borrowings	1,069,409	920,102	902,015
Accrued expenses and other liabilities	209,741	219,712	186,006
Total liabilities	$ 10,619,097	$ 10,181,787	$ 9,110,602
Shareholders' Equity
Preferred stock, 2,000 shares authorized, no shares issued or outstanding
Common stock, $1.00 per share stated value, 150,000 shares authorized, 115,205, 116,847 and 105,851 shares issued and outstanding, respectively	$ 115,205	$ 116,847	$ 105,851
Capital surplus	1,098,384	1,118,292	975,354
Retained earnings	281,196	262,180	229,467
Accumulated other comprehensive income (loss), net of tax	(38,062)	(31,555)	(33,341)
Total shareholders' equity	1,456,723	1,465,764	1,277,331
Total liabilities and shareholders' equity	12,075,820	11,647,551	10,387,933
U.S. Treasury [Member]
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	12,171	15,166	11,186
U.S. Government-Sponsored Entities and Agencies [Member]
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	695,074	685,951	623,672
Mortgage-Backed Securities - Agency [Member]
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	1,104,145	1,241,662	1,220,293
States and Political Subdivisions [Member]
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	388,039	314,541	309,106
Other Debt Securities Including Pooled Trust Preferred Securities [Member]
Investment securities - available-for-sale, at fair value:
Total investment securities - available-for-sale	$ 373,092	$ 370,511	$ 348,860