Loans and Asset Quality Information (Details 9) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Provisions	$ 7,073	$ 9,146	$ 35,095	$ 31,423
Ending balance - total	2,137,074	2,058,724	2,137,074	2,058,724	2,069,152
Commercial, financial and agricultural
Beginning balance	5,061	3,905	3,780	4,731	4,731
Charge-offs	(571)	(102)	(2,633)	(1,998)	(2,703)
Recoveries	219	15	253	51	389
Provisions	468	161	3,777	1,195	1,363
Ending balance	5,177	3,979	5,177	3,979	3,780
Individually evaluated for impairment	871	145	871	145	60
Collectively evaluated for impairment	4,306	3,834	4,306	3,834	3,720
Loans acquired with deteriorated credit quality
Ending balance - total	171,716	169,545	171,716	169,545	172,357
Individually evaluated for impairment	951	2,377	951	2,377	2,526
Collectively evaluated for impairment	170,765	167,168	170,765	167,168	169,831
Loans acquired with deteriorated credit quality
Real Estate construction, land development & other land loans
Beginning balance	17,819	11,790
Charge-offs	(4,628)	(3,937)
Recoveries	487	220
Provisions	1,109	3,215
Real estate residential, farmland and mutli-family
Beginning balance	14,959	12,084	13,532	11,283	11,283
Charge-offs	(1,399)	(1,349)	(5,635)	(6,945)	(9,045)
Recoveries	92	286	346	579	719
Provisions	1,731	1,456	7,140	7,560	10,575
Ending balance	15,383	12,477	15,383	12,477	13,532
Individually evaluated for impairment	369	49	369	49	150
Collectively evaluated for impairment	15,014	12,428	15,014	12,428	13,382
Loans acquired with deteriorated credit quality
Ending balance - total	826,953	785,412	826,953	785,412	795,655
Individually evaluated for impairment	5,546	12,940	5,546	12,940	11,880
Collectively evaluated for impairment	821,407	772,472	821,407	772,472	783,775
Loans acquired with deteriorated credit quality
Real estate home equity lines of credit
Beginning balance	2,146	1,849	1,690	3,634	3,634
Charge-offs	(1,098)	(189)	(1,830)	(953)	(1,147)
Recoveries	10	10	129	53	107
Provisions	825	97	1,894	(967)	(904)
Ending balance	1,883	1,767	1,883	1,767	1,690
Individually evaluated for impairment
Collectively evaluated for impairment	1,883	1,767	1,883	1,767	1,690
Loans acquired with deteriorated credit quality
Ending balance - total	203,154	211,999	203,154	211,999	207,436
Individually evaluated for impairment	275	528	275	528	527
Collectively evaluated for impairment	202,879	211,471	202,879	211,471	206,909
Loans acquired with deteriorated credit quality
Real estate commercial
Beginning balance	5,719	2,859	3,414	3,972	3,972
Charge-offs	(1,247)	(1,149)	(3,417)	(2,529)	(3,355)
Recoveries	21	5	68	33	37
Provisions	1,354	1,303	5,782	1,542	2,760
Ending balance	5,847	3,018	5,847	3,018	3,414
Individually evaluated for impairment	1,276	25	1,276	25	200
Collectively evaluated for impairment	4,571	2,993	4,571	2,993	3,214
Loans acquired with deteriorated credit quality
Ending balance - total	640,578	576,459	640,578	576,459	587,183
Individually evaluated for impairment	29,901	30,833	29,901	30,833	30,846
Collectively evaluated for impairment	611,487	545,626	611,487	545,626	556,337
Loans acquired with deteriorated credit quality
Consumer
Beginning balance	1,791	1,960	1,872	1,961	1,961
Charge-offs	(307)	(173)	(993)	(533)	(845)
Recoveries	82	9	214	112	182
Provisions	315	78	788	334	574
Ending balance	1,881	1,874	1,881	1,874	1,872
Individually evaluated for impairment
Collectively evaluated for impairment	1,881	1,874	1,881	1,874	1,872
Loans acquired with deteriorated credit quality
Ending balance - total	56,235	59,653	56,235	59,653	58,436
Individually evaluated for impairment		17		17	12
Collectively evaluated for impairment	56,235	59,636	56,235	59,636	58,424
Loans acquired with deteriorated credit quality
Unallocated
Beginning balance	28	18	16	174	174
Charge-offs		(179)		(415)	(524)
Recoveries		24		97	93
Provisions	168	131	180	138	273
Ending balance	196	(6)	196	(6)	16
Individually evaluated for impairment
Collectively evaluated for impairment	196	(6)	196	(6)	16
Loans acquired with deteriorated credit quality
Ending balance - total
Individually evaluated for impairment
Collectively evaluated for impairment
Loans acquired with deteriorated credit quality
Non-covered
Beginning balance	47,253	34,465
Charge-offs	(9,250)	(7,078)
Recoveries	911	569
Provisions	5,970	6,441
Real Estate construction, land development and other land loans
Beginning balance			11,306	12,520	12,520
Charge-offs			(7,480)	(13,519)	(16,240)
Recoveries			801	471	1,142
Provisions			10,160	11,816	13,884
Ending balance	14,787	11,288	14,787	11,288	11,306
Individually evaluated for impairment	109	655	109	655	607
Collectively evaluated for impairment	14,678	10,633	14,678	10,633	10,699
Loans acquired with deteriorated credit quality
Ending balance - total	236,960	254,361	236,960	254,361	246,805
Individually evaluated for impairment	14,187	39,651	14,187	39,651	34,750
Collectively evaluated for impairment	222,773	214,710	222,773	214,710	212,055
Loans acquired with deteriorated credit quality		922		922	920
Non-covered
Beginning balance			35,610	38,275	38,275
Charge-offs			(21,988)	(26,892)	(33,859)
Recoveries			1,811	1,396	2,669
Provisions			29,721	21,618	28,525
Ending balance	45,154	34,397	45,154	34,397	35,610
Individually evaluated for impairment	2,625	874	2,625	874	1,017
Collectively evaluated for impairment	42,529	33,523	42,529	33,523	34,593
Loans acquired with deteriorated credit quality
Ending balance - total	2,135,596	2,135,596	2,135,596	2,135,596	2,067,872
Individually evaluated for impairment	50,050	86,346	50,050	86,346	80,541
Collectively evaluated for impairment	2,085,546	1,971,083	2,085,546	1,971,083	1,987,331
Loans acquired with deteriorated credit quality		922		922	920
Non-covered | Real estate residential, farmland and mutli-family
Ending balance - total	826,953		826,953		795,655
Non-covered | Real estate home equity lines of credit
Ending balance - total	203,154		203,154		207,436
Non-covered | Real estate commercial
Ending balance - total	640,578		640,578		587,183
Non-covered | Consumer
Ending balance - total	56,235		56,235		58,436
Non-covered | Real Estate construction, land development and other land loans
Ending balance - total	$ 236,960		$ 236,960		$ 246,805