Portfolio Loans Not Covered by Loss Share ("Non-covered") - Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Loans - Ending Balance:
Total	$ 1,948,994		$ 1,897,074
Non-Covered Loans
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	8,551		10,729
Collectively evaluated for impairment	27,753		27,260
Total	36,304	37,596	37,989
Loans - Ending Balance:
Individually evaluated for Impairment	40,555		41,622
Collectively evaluated for impairment	1,908,439		1,855,452
Total	1,949,270		1,897,412
Total	1,948,994		1,897,074
Non-Covered Loans | Commercial & Industrial
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,098		3,214
Collectively evaluated for impairment	6,883		8,731
Total	8,981	12,385	11,945
Loans - Ending Balance:
Individually evaluated for Impairment	4,667		5,634
Collectively evaluated for impairment	836,716		757,568
Total	841,383		763,202
Non-Covered Loans | Real Estate
Loans - Ending Balance:
Total	1,093,867		1,122,751
Non-Covered Loans | Real Estate | Commercial Real Estate Owner Occupied
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,257		1,377
Collectively evaluated for impairment	3,049		4,920
Total	5,306	6,784	6,297
Loans - Ending Balance:
Individually evaluated for Impairment	10,130		4,572
Collectively evaluated for impairment	312,361		329,844
Total	322,491		334,416
Non-Covered Loans | Real Estate | Commercial Real Estate Investor Owned
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,244		2,315
Collectively evaluated for impairment	7,978		4,436
Total	10,222	6,797	6,751
Loans - Ending Balance:
Individually evaluated for Impairment	9,937		11,127
Collectively evaluated for impairment	469,555		466,027
Total	479,492		477,154
Non-Covered Loans | Real Estate | Construction and Land Development
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	1,408		2,927
Collectively evaluated for impairment	4,041		2,920
Total	5,449	5,412	5,847
Loans - Ending Balance:
Individually evaluated for Impairment	11,278		14,767
Collectively evaluated for impairment	131,196		125,380
Total	142,474		140,147
Non-Covered Loans | Real Estate | Residential Real Estate
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	544		896
Collectively evaluated for impairment	2,705		3,035
Total	3,249	3,370	3,931
Loans - Ending Balance:
Individually evaluated for Impairment	4,543		5,522
Collectively evaluated for impairment	144,867		165,512
Total	149,410		171,034
Non-Covered Loans | Consumer & Other
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	19		14
Total	19	16	14
Loans - Ending Balance:
Individually evaluated for Impairment	0		0
Collectively evaluated for impairment	13,744		11,121
Total	14,020		11,459
Total	13,744		11,121
Non-Covered Loans | Qualitative Adjustment
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	3,078		3,204
Total	3,078	2,832	3,204
Loans - Ending Balance:
Individually evaluated for Impairment	0		0
Collectively evaluated for impairment	0		0
Total	$ 0		$ 0