Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Cash and cash equivalents:
Cash and due from banks	$ 641,502	$ 229,901	$ 269,480
Interest-bearing deposits with banks	7,333	7,456	7,382
Federal funds sold and securities purchased under agreements to resell	240,545	180,512	226,166
Total cash and cash equivalents	889,380	417,869	503,028
Investment securities:
Securities held to maturity (fair value of $9,758, $10,233 and $11,019, respectively)	9,314	9,659	10,389
Securities available for sale, at fair value	885,798	806,766	805,114
Other investments	9,031	10,518	10,518
Total investment securities	904,143	826,943	826,021
Loans held for sale	48,985	61,934	57,683
Loans:
Loans, gross	3,994,716	3,467,826	3,304,708
Less allowance for non-acquired loan losses	(35,116)	(34,539)	(34,804)
Loans, net	5,835,646	5,680,688	5,627,739
FDIC indemnification asset	7,942	22,161	30,983
Other real estate owned (covered of $5,465, $16,227, and $18,961, respectively; non-covered of $25,913, $26,499, and $32,289, respectively)	31,378	42,726	51,250
Premises and equipment, net	174,662	171,772	173,425
Bank owned life insurance	100,967	99,140	98,505
Deferred tax assets	40,090	42,692	60,322
Mortgage servicing rights	24,665	21,601	22,052
Core deposit and other intangibles	49,982	49,239	51,291
Goodwill	338,342	317,688	317,688
Other assets	53,694	71,774	60,101
Total assets	8,499,876	7,826,227	7,880,088
Deposits:
Noninterest-bearing	1,927,309	1,639,953	1,654,308
Interest-bearing	5,150,700	4,821,092	4,863,920
Total deposits	7,078,009	6,461,045	6,518,228
Federal funds purchased and securities sold under agreements to repurchase	260,521	221,541	231,229
Other borrowings	55,107	101,210	101,127
Other liabilities	57,927	57,511	62,509
Total liabilities	$ 7,451,564	$ 6,841,307	$ 6,913,093
Shareholders' equity:
Preferred stock - $.01 par value; authorized 10,000,000 shares; no shares issued and outstanding
Common stock - $2.50 par value; authorized 40,000,000 shares; 24,211,793, 24,150,702 and 24,135,220 shares issued and outstanding, respectively	$ 60,529	$ 60,377	$ 60,338
Surplus	706,227	701,764	700,579
Retained earnings	279,681	223,156	207,219
Accumulated other comprehensive loss	1,875	(377)	(1,141)
Total shareholders' equity	1,048,312	984,920	966,995
Total liabilities and shareholders' equity	8,499,876	7,826,227	7,880,088
Acquired loans
Loans:
Loans, net	768,606	919,402	980,492
Non-acquired loans
Loans:
Loans, net	$ 1,107,440	$ 1,327,999	$ 1,377,343