Loans and Allowance for Loan Losses (Details 11) (Acquired loans, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Loans and Allowance for Loan Losses
30-59 Days Past Due	$ 20,338	$ 19,213	$ 9,185
60-89 Days Past Due	10,822	13,431	4,603
90+ Days Past Due	79,562	83,085	82,841
Total Past Due	110,722	115,729	96,629
Current	884,533	959,013	272,515
Total acquired loans	995,255	1,074,742	369,144
Commercial Loans Greater Than or Equal to $1 Million-CBT
Loans and Allowance for Loan Losses
Total acquired loans	48,110		56,316
Commercial real estate
Loans and Allowance for Loan Losses
Total acquired loans	347,238		100,797
Commercial Real Estate - Construction & Land Development
Loans and Allowance for Loan Losses
Total acquired loans	110,059		44,339
Residential real estate
Loans and Allowance for Loan Losses
Total acquired loans	336,030		129,189
Consumer
Loans and Allowance for Loan Losses
Total acquired loans	13,168		8,583
Commercial and industrial
Loans and Allowance for Loan Losses
Total acquired loans	65,684		24,520
Single Pay
Loans and Allowance for Loan Losses
Total acquired loans	4,732		5,400
FASB ASC Topic 310-20 Loans
Loans and Allowance for Loan Losses
Total acquired loans	70,234	73,215	73,215
Covered loans
Loans and Allowance for Loan Losses
30-59 Days Past Due	8,842	8,766	8,954
60-89 Days Past Due	2,638	8,850	4,573
90+ Days Past Due	55,610	64,195	82,755
Total Past Due	67,090	81,811	96,282
Current	189,976	200,917	266,769
Total acquired loans	257,066	282,728	363,051
Covered loans | Commercial Loans Greater Than or Equal to $1 Million-CBT
Loans and Allowance for Loan Losses
30-59 Days Past Due		922	2,507
60-89 Days Past Due		993	1,639
90+ Days Past Due	22,667	22,471	23,743
Total Past Due	22,667	24,386	27,889
Current	25,443	25,298	28,427
Total acquired loans	48,110	49,684	56,316
Covered loans | Commercial real estate
Loans and Allowance for Loan Losses
30-59 Days Past Due	2,675	3,154	882
60-89 Days Past Due	737	1,536	382
90+ Days Past Due	7,089	12,162	19,893
Total Past Due	10,501	16,852	21,157
Current	42,471	46,110	78,677
Total acquired loans	52,972	62,962	99,834
Covered loans | Commercial Real Estate - Construction & Land Development
Loans and Allowance for Loan Losses
30-59 Days Past Due	2,927	1,381	945
60-89 Days Past Due	371	220	412
90+ Days Past Due	7,842	11,615	16,030
Total Past Due	11,140	13,216	17,387
Current	16,517	19,359	26,869
Total acquired loans	27,657	32,575	44,256
Covered loans | Residential real estate
Loans and Allowance for Loan Losses
30-59 Days Past Due	2,831	2,502	3,961
60-89 Days Past Due	878	2,636	1,535
90+ Days Past Due	9,254	12,328	13,427
Total Past Due	12,963	17,466	18,923
Current	84,809	87,345	109,287
Total acquired loans	97,772	104,811	128,210
Covered loans | Consumer
Loans and Allowance for Loan Losses
30-59 Days Past Due	78	67	105
60-89 Days Past Due	137	19	250
90+ Days Past Due	648	687	936
Total Past Due	863	773	1,291
Current	2,982	3,551	4,854
Total acquired loans	3,845	4,324	6,145
Covered loans | Commercial and industrial
Loans and Allowance for Loan Losses
30-59 Days Past Due	280	739	554
60-89 Days Past Due	515	190	355
90+ Days Past Due	3,987	4,870	5,057
Total Past Due	4,782	5,799	5,966
Current	17,196	17,801	16,924
Total acquired loans	21,978	23,600	22,890
Covered loans | Single Pay
Loans and Allowance for Loan Losses
30-59 Days Past Due	51	1
60-89 Days Past Due		3,256
90+ Days Past Due	4,123	62	3,669
Total Past Due	4,174	3,319	3,669
Current	558	1,453	1,731
Total acquired loans	4,732	4,772	5,400
Non-covered loans
Loans and Allowance for Loan Losses
30-59 Days Past Due	11,496	10,447	231
60-89 Days Past Due	8,184	4,581	30
90+ Days Past Due	23,952	18,890	86
Total Past Due	43,632	33,918	347
Current	694,557	758,096	5,746
Total acquired loans	738,189	792,014	6,093
Non-covered loans | Commercial real estate
Loans and Allowance for Loan Losses
30-59 Days Past Due	4,427	2,712
60-89 Days Past Due	1,236	770
90+ Days Past Due	7,779	5,326
Total Past Due	13,442	8,808
Current	280,824	301,154	963
Total acquired loans	294,266	309,962	963
Non-covered loans | Commercial Real Estate - Construction & Land Development
Loans and Allowance for Loan Losses
30-59 Days Past Due	4,779	1,595
60-89 Days Past Due	1,025	1,353
90+ Days Past Due	5,533	7,103
Total Past Due	11,337	10,051
Current	71,065	87,825	83
Total acquired loans	82,402	97,876	83
Non-covered loans | Residential real estate
Loans and Allowance for Loan Losses
30-59 Days Past Due	1,627	5,109	166
60-89 Days Past Due	4,590	2,193
90+ Days Past Due	9,813	5,987
Total Past Due	16,030	13,289	166
Current	222,228	237,027	813
Total acquired loans	238,258	250,316	979
Non-covered loans | Consumer
Loans and Allowance for Loan Losses
30-59 Days Past Due	84	114	63
60-89 Days Past Due	39	57	30
90+ Days Past Due	23	49	76
Total Past Due	146	220	169
Current	9,177	11,141	2,269
Total acquired loans	9,323	11,361	2,438
Non-covered loans | Commercial and industrial
Loans and Allowance for Loan Losses
30-59 Days Past Due	126	529	2
60-89 Days Past Due	553	97
90+ Days Past Due	404	277	10
Total Past Due	1,083	903	12
Current	42,623	48,381	1,618
Total acquired loans	43,706	49,284	1,630
Non-covered loans | FASB ASC Topic 310-20 Loans
Loans and Allowance for Loan Losses
30-59 Days Past Due	453	388
60-89 Days Past Due	741	111
90+ Days Past Due	400	148
Total Past Due	1,594	647
Current	68,640	72,568
Total acquired loans	$ 70,234	$ 73,215