Portfolio Loans Not Covered by Loss Share ("Non-covered") - Summary of Allowance for Loan Losses for Non-covered Loans by Portfolio Class and Category (Details) (Non-Covered Loans, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Allowance for Loan Losses [Roll Forward]
Balance	$ 34,330
Provision charged to expense	1,853
Losses charged off	(4,780)
Recoveries	1,049
Balance	32,452
Commercial & Industrial
Allowance for Loan Losses [Roll Forward]
Balance	10,064
Provision charged to expense	120
Losses charged off	(206)
Recoveries	298
Balance	10,276
Real Estate | Commercial Real Estate Owner Occupied
Allowance for Loan Losses [Roll Forward]
Balance	4,192
Provision charged to expense	179
Losses charged off	(312)
Recoveries	5
Balance	4,064
Real Estate | Commercial Real Estate Investor Owned
Allowance for Loan Losses [Roll Forward]
Balance	10,403
Provision charged to expense	953
Losses charged off	(3,052)
Recoveries	336
Balance	8,640
Real Estate | Construction and Land Development
Allowance for Loan Losses [Roll Forward]
Balance	5,239
Provision charged to expense	(127)
Losses charged off	(190)
Recoveries	14
Balance	4,936
Real Estate | Residential Real Estate
Allowance for Loan Losses [Roll Forward]
Balance	2,026
Provision charged to expense	675
Losses charged off	(986)
Recoveries	396
Balance	2,111
Consumer & Other
Allowance for Loan Losses [Roll Forward]
Balance	31
Provision charged to expense	46
Losses charged off	(34)
Recoveries	0
Balance	43
Qualitative Adjustment
Allowance for Loan Losses [Roll Forward]
Balance	2,375
Provision charged to expense	7
Losses charged off	0
Recoveries	0
Balance	$ 2,382