Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Cash and cash equivalents:
Cash and due from banks	$ 227,326	$ 185,708	$ 329,942
Interest-bearing deposits with banks	5,743	16,018	1,870
Federal funds sold and securities purchased under agreements to resell	262,800	179,004	71,410
Total cash and cash equivalents	495,869	380,730	403,222
Investment securities:
Securities held to maturity (fair value of $15,555, $16,553, and $17,664, respectively)	14,598	15,440	16,568
Securities available for sale, at fair value	510,852	534,883	322,588
Other investments	7,805	9,768	18,292
Total investment securities	533,255	560,091	357,448
Loans held for sale	50,449	65,279	34,706
Loans:
Loans, net	3,526,607	3,569,235	2,724,496
FDIC receivable for loss share agreements	124,340	146,171	231,331
Premises and equipment, net	110,792	115,583	93,209
Goodwill	100,487	100,487	62,888
Other real estate owned (covered of $34,244, $34,257, and $61,788, respectively; non-covered of $36,446, $32,248, and $21,381, respectively)	70,690	66,505	83,169
Bank owned life insurance	43,008	42,737	22,233
Core deposit and other intangibles	24,180	25,199	11,038
Other assets	62,252	64,296	22,603
Total assets	5,141,929	5,136,313	4,046,343
Deposits:
Noninterest-bearing	1,002,662	981,963	757,777
Interest-bearing	3,216,694	3,316,397	2,598,860
Total deposits	4,219,356	4,298,360	3,356,637
Federal funds purchased and securities sold under agreements to repurchase	328,701	238,621	235,412
Other borrowings	54,638	54,897	46,397
Other liabilities	25,023	36,886	21,390
Total liabilities	4,627,718	4,628,764	3,659,836
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; 17,017,904, 16,937,464, and 14,052,177 shares issued and outstanding	42,545	42,344	35,130
Surplus	329,636	328,843	233,422
Retained earnings	143,573	135,986	120,837
Accumulated other comprehensive income (loss)	(1,543)	376	(2,882)
Total shareholders' equity	514,211	507,549	386,507
Total liabilities and shareholders' equity	5,141,929	5,136,313	4,046,343
Acquired loans
Loans:
Loans, gross	995,255	1,074,742	369,144
Loans, allowance	(31,277)	(32,132)	(34,355)
Non-acquired loans
Loans:
Loans, gross	2,604,298	2,571,003	2,437,314
Loans, allowance	$ (41,669)	$ (44,378)	$ (47,607)