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	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Loans - Ending Balance:
Total	$ 1,987,166			$ 1,897,074
Non-Covered Loans
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	6,787			10,729
Collectively evaluated for impairment	27,435			27,260
Total	34,222	36,304	37,596	37,989
Loans - Ending Balance:
Individually evaluated for Impairment	32,058			41,622
Collectively evaluated for impairment	1,955,108			1,855,452
Total	1,987,144			1,897,412
Total	1,987,166			1,897,074
Non-Covered Loans | Commercial & Industrial
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	1,165			3,214
Collectively evaluated for impairment	6,275			8,731
Total	7,440	8,981	12,385	11,945
Loans - Ending Balance:
Individually evaluated for Impairment	2,849			5,634
Collectively evaluated for impairment	877,545			757,568
Total	880,394			763,202
Non-Covered Loans | Real Estate
Loans - Ending Balance:
Total	1,095,056			1,122,751
Non-Covered Loans | Real Estate | Commercial Real Estate Owner Occupied
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	379			1,377
Collectively evaluated for impairment	3,565			4,920
Total	3,944	5,306	6,784	6,297
Loans - Ending Balance:
Individually evaluated for Impairment	5,584			4,572
Collectively evaluated for impairment	319,795			329,844
Total	325,379			334,416
Non-Covered Loans | Real Estate | Commercial Real Estate Investor Owned
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,199			2,315
Collectively evaluated for impairment	8,002			4,436
Total	10,201	10,222	6,797	6,751
Loans - Ending Balance:
Individually evaluated for Impairment	9,647			11,127
Collectively evaluated for impairment	466,854			466,027
Total	476,501			477,154
Non-Covered Loans | Real Estate | Construction and Land Development
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,538			2,927
Collectively evaluated for impairment	4,528			2,920
Total	7,066	5,449	5,412	5,847
Loans - Ending Balance:
Individually evaluated for Impairment	10,095			14,767
Collectively evaluated for impairment	136,141			125,380
Total	146,236			140,147
Non-Covered Loans | Real Estate | Residential Real Estate
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	506			896
Collectively evaluated for impairment	1,931			3,035
Total	2,437	3,249	3,370	3,931
Loans - Ending Balance:
Individually evaluated for Impairment	3,883			5,522
Collectively evaluated for impairment	143,057			165,512
Total	146,940			171,034
Non-Covered Loans | Consumer & Other
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	23			14
Total	23	19	16	14
Loans - Ending Balance:
Individually evaluated for Impairment	0			0
Collectively evaluated for impairment	11,716			11,121
Total	11,694			11,459
Total	11,716			11,121
Non-Covered Loans | Qualitative Adjustment
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	3,111			3,204
Total	3,111	3,078	2,832	3,204
Loans - Ending Balance:
Individually evaluated for Impairment	0			0
Collectively evaluated for impairment	0			0
Total	$ 0			$ 0