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	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Cash collected and recognized as interest income	$ 15	$ 126
Loans - Ending Balance:
Total	2,085,872		2,106,039
Non-Covered Loans
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	6,040		8,176
Collectively evaluated for impairment	26,412		26,154
Total	32,452		34,330
Loans - Ending Balance:
Individually evaluated for Impairment	30,379		38,727
Collectively evaluated for impairment	2,055,493		2,067,312
Total	2,085,428		2,106,028
Total	2,085,872		2,106,039
Non-Covered Loans | Commercial & Industrial
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	3,542		3,446
Collectively evaluated for impairment	6,734		6,618
Total	10,276		10,064
Loans - Ending Balance:
Individually evaluated for Impairment	7,812		8,934
Collectively evaluated for impairment	941,359		953,950
Total	949,171		962,884
Non-Covered Loans | Real Estate
Loans - Ending Balance:
Total	1,116,538		1,126,178
Non-Covered Loans | Real Estate | Commercial Real Estate Owner Occupied
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	5		339
Collectively evaluated for impairment	4,059		3,853
Total	4,064		4,192
Loans - Ending Balance:
Individually evaluated for Impairment	3,060		5,772
Collectively evaluated for impairment	336,026		327,470
Total	339,086		333,242
Non-Covered Loans | Real Estate | Commercial Real Estate Investor Owned
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	1,835		3,400
Collectively evaluated for impairment	6,805		7,003
Total	8,640		10,403
Loans - Ending Balance:
Individually evaluated for Impairment	11,592		16,762
Collectively evaluated for impairment	461,411		469,705
Total	473,003		486,467
Non-Covered Loans | Real Estate | Construction and Land Development
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	590		732
Collectively evaluated for impairment	4,346		4,507
Total	4,936		5,239
Loans - Ending Balance:
Individually evaluated for Impairment	5,387		4,695
Collectively evaluated for impairment	150,834		156,216
Total	156,221		160,911
Non-Covered Loans | Real Estate | Residential Real Estate
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	68		259
Collectively evaluated for impairment	2,043		1,767
Total	2,111		2,026
Loans - Ending Balance:
Individually evaluated for Impairment	2,528		2,564
Collectively evaluated for impairment	145,700		142,994
Total	148,228		145,558
Non-Covered Loans | Consumer & Other
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	43		31
Total	43		31
Loans - Ending Balance:
Individually evaluated for Impairment	0		0
Collectively evaluated for impairment	20,163		16,977
Total	19,719		16,966
Total	20,163		16,977
Non-Covered Loans | Qualitative Adjustment
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	2,382		2,375
Total	2,382		2,375
Loans - Ending Balance:
Individually evaluated for Impairment	0		0
Collectively evaluated for impairment	0		0
Total	$ 0		$ 0