Loans (Details 6) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Originated Portfolio [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	$ 22,734	$ 26,252	$ 29,983
Financing receivable, recorded investment 61 to 89 days past due	4,331	11,167	11,167
Financing receivable, recorded investment accruing loans past due 90 days or more	2,098	3,817	3,015
Financing receivable, recorded investment, Nonaccrual loans	78,324	78,394	91,112
Financing receivable recorded investment, Total past due	107,487	119,630	135,277
Financing receivable, recorded investment, current	3,499,060	3,218,872	3,129,777
Financing receivable, recorded investment, Total loans	3,606,547	3,338,502	3,265,054
Originated Portfolio [Member] | Commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	9,707	5,207	7,471
Financing receivable, recorded investment 61 to 89 days past due	1,374	6,268	3,364
Financing receivable, recorded investment accruing loans past due 90 days or more	273	1,381	282
Financing receivable, recorded investment, Nonaccrual loans	15,217	10,726	10,804
Financing receivable recorded investment, Total past due	26,571	23,582	21,921
Financing receivable, recorded investment, current	812,111	739,953	704,885
Financing receivable, recorded investment, Total loans	838,682	763,535	726,806
Originated Portfolio [Member] | Real estate commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	4,929	9,967	10,104
Financing receivable, recorded investment 61 to 89 days past due	1,660	3,241	4,832
Financing receivable, recorded investment accruing loans past due 90 days or more	247	374	415
Financing receivable, recorded investment, Nonaccrual loans	41,311	44,438	48,854
Financing receivable recorded investment, Total past due	48,147	58,020	64,205
Financing receivable, recorded investment, current	856,252	757,047	737,111
Financing receivable, recorded investment, Total loans	904,399	815,067	801,316
Originated Portfolio [Member] | Real estate construction [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	214
Financing receivable, recorded investment 61 to 89 days past due	0	0	288
Financing receivable, recorded investment accruing loans past due 90 days or more	0	287	0
Financing receivable, recorded investment, Nonaccrual loans	933	0	0
Financing receivable recorded investment, Total past due	933	287	502
Financing receivable, recorded investment, current	37,364	54,029	52,882
Financing receivable, recorded investment, Total loans	38,297	54,316	53,384
Originated Portfolio [Member] | Land development [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	48	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	349
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	5,731	6,190	7,877
Financing receivable recorded investment, Total past due	5,779	6,190	8,226
Financing receivable, recorded investment, current	18,705	24,065	23,291
Financing receivable, recorded investment, Total loans	24,484	30,255	31,517
Originated Portfolio [Member] | Real estate residential [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	3,208	5,591	5,793
Financing receivable, recorded investment 61 to 89 days past due	97	76	247
Financing receivable, recorded investment accruing loans past due 90 days or more	431	752	974
Financing receivable, recorded investment, Nonaccrual loans	11,307	12,573	17,544
Financing receivable recorded investment, Total past due	15,043	18,992	24,558
Financing receivable, recorded investment, current	849,982	821,760	793,109
Financing receivable, recorded investment, Total loans	865,025	840,752	817,667
Originated Portfolio [Member] | Consumer installment [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	3,299	3,449	4,578
Financing receivable, recorded investment 61 to 89 days past due	470	1,174	775
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	876	1,707	2,931
Financing receivable recorded investment, Total past due	4,645	6,330	8,284
Financing receivable, recorded investment, current	531,594	474,614	514,056
Financing receivable, recorded investment, Total loans	536,239	480,944	522,340
Originated Portfolio [Member] | Home equity [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	1,543	2,038	1,823
Financing receivable, recorded investment 61 to 89 days past due	730	408	1,312
Financing receivable, recorded investment accruing loans past due 90 days or more	1,147	1,023	1,344
Financing receivable, recorded investment, Nonaccrual loans	2,949	2,760	3,102
Financing receivable recorded investment, Total past due	6,369	6,229	7,581
Financing receivable, recorded investment, current	393,052	347,404	304,443
Financing receivable, recorded investment, Total loans	399,421	353,633	312,024
Acquired Portfolio [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	1,498	3,192	823
Financing receivable, recorded investment 61 to 89 days past due	54	273	1,105
Financing receivable, recorded investment accruing loans past due 90 days or more	9,391	17,375	19,732
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	10,943	20,840	21,660
Financing receivable, recorded investment, current	401,669	471,943	473,712
Financing receivable, recorded investment, Total loans	412,612	492,783	495,372
Acquired Portfolio [Member] | Commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	394	540
Financing receivable, recorded investment 61 to 89 days past due	15	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	3,356	7,808	10,515
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	3,371	8,202	11,055
Financing receivable, recorded investment, current	109,885	123,413	121,108
Financing receivable, recorded investment, Total loans	113,256	131,615	132,163
Acquired Portfolio [Member] | Real estate commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	1,262	1,820	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	2,390	2,592	2,864
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	3,652	4,412	2,864
Financing receivable, recorded investment, current	209,022	252,520	251,912
Financing receivable, recorded investment, Total loans	212,674	256,932	254,776
Acquired Portfolio [Member] | Real estate construction [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	0	156	143
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	0	156	143
Financing receivable, recorded investment, current	17,774	18,883	19,324
Financing receivable, recorded investment, Total loans	17,774	19,039	19,467
Acquired Portfolio [Member] | Land development [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	3,038	4,780	4,799
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	3,038	4,780	4,799
Financing receivable, recorded investment, current	7,289	9,786	10,662
Financing receivable, recorded investment, Total loans	10,327	14,566	15,461
Acquired Portfolio [Member] | Real estate residential [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	80	288	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	766
Financing receivable, recorded investment accruing loans past due 90 days or more	343	1,577	860
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	423	1,865	1,626
Financing receivable, recorded investment, current	14,847	19,099	20,751
Financing receivable, recorded investment, Total loans	15,270	20,964	22,377
Acquired Portfolio [Member] | Consumer installment [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	18	49	47
Financing receivable, recorded investment 61 to 89 days past due	0	11	83
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	18	60	130
Financing receivable, recorded investment, current	2,155	3,054	4,103
Financing receivable, recorded investment, Total loans	2,173	3,114	4,233
Acquired Portfolio [Member] | Home equity [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	138	641	236
Financing receivable, recorded investment 61 to 89 days past due	39	262	256
Financing receivable, recorded investment accruing loans past due 90 days or more	264	462	551
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	441	1,365	1,043
Financing receivable, recorded investment, current	40,697	45,188	45,852
Financing receivable, recorded investment, Total loans	$ 41,138	$ 46,553	$ 46,895