Non-Covered Loans and Allowance for Non-Covered Loan Losses (Details 7) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
Changes in the allowance for loan losses
Balance, beginning of period		$ 3,409
Provision charged to operations	10,658	34,952
Balance, end of period	33,180	33,180
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans	3,310,224	3,310,224	3,152,396
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans	33,180	33,180
Non-covered loans
Changes in the allowance for loan losses
Balance, beginning of period	26,237	3,409
Provision charged to operations	10,658	34,952
Loans charged off	(3,800)	(8,061)
Recoveries on charged off loans	85	2,880
Balance, end of period	33,180	33,180
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	1,101	1,101
Loans collectively evaluated for impairment	3,169,899	3,169,899	2,985,616
Total loans	3,310,224	3,310,224	3,152,396
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	30,169	30,169	3,409
Total loans	33,180	33,180
Non-covered loans | Commercial and Industrial
Changes in the allowance for loan losses
Balance, beginning of period	13,806	1,845
Provision charged to operations	8,879	22,519
Loans charged off	(3,220)	(7,314)
Recoveries on charged off loans	42	2,457
Balance, end of period	19,507	19,507
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	940	940
Loans collectively evaluated for impairment	1,565,975	1,565,975	1,588,907
Total loans	1,625,422	1,625,422	1,660,293
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	16,775	16,775	1,845
Total loans	19,507	19,507
Non-covered loans | Real estate
Changes in the allowance for loan losses
Balance, beginning of period	5,339	977
Provision charged to operations	1,776	6,033
Loans charged off	(53)	(149)
Recoveries on charged off loans	26	227
Balance, end of period	7,088	7,088
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	161	161
Loans collectively evaluated for impairment	1,275,180	1,275,180	1,122,667
Total loans	1,322,054	1,322,054	1,184,914
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	6,810	6,810	977
Total loans	7,088	7,088
Non-covered loans | Construction and Land Development
Changes in the allowance for loan losses
Balance, beginning of period	7,050	582
Provision charged to operations	6	6,323
Loans charged off	(524)	(524)
Recoveries on charged off loans	2	153
Balance, end of period	6,534	6,534
Loan portfolio distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	285,751	285,751	247,413
Total loans	310,392	310,392	280,483
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	6,533	6,533	582
Total loans	6,534	6,534
Non-covered loans | Consumer
Changes in the allowance for loan losses
Balance, beginning of period	42	5
Provision charged to operations	(3)	77
Loans charged off	(3)	(74)
Recoveries on charged off loans	15	43
Balance, end of period	51	51
Loan portfolio distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	42,993	42,993	26,629
Total loans	52,356	52,356	26,706
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment	51	51	5
Total loans	51	51
Non-covered loans | Acquired performing loans
Allowance for loan losses
Additional allowance recorded when allowance is less than remaining fair value of discount		0
Non-covered loans | PCI loans
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	139,224	139,224	166,780
Total loans	139,224	139,224	166,780
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	3,011	3,011
Non-covered loans | PCI loans | Commercial and Industrial
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	58,507	58,507	71,386
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	2,732	2,732
Non-covered loans | PCI loans | Real estate
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	46,713	46,713	62,247
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	278	278
Non-covered loans | PCI loans | Construction and Land Development
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	24,641	24,641	33,070
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	1	1
Non-covered loans | PCI loans | Consumer
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment	9,363	9,363	77
Total loans	9,363	9,363	77
Non-covered loans | Acquired loans
Allowance for loan losses
Carryover of the allowance for loan losses recorded		$ 0