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
	Jun. 30, 2013	Mar. 31, 2013
Allowance for Loan Losses [Roll Forward]
Balance	$ 32,452	$ 34,330
Provision charged to expense	(4,295)	1,853
Losses charged off	(752)	(4,780)
Recoveries	214	1,049
Balance	27,619	32,452
Commercial & Industrial
Allowance for Loan Losses [Roll Forward]
Balance	10,276	10,064
Provision charged to expense	(320)	120
Losses charged off	(400)	(206)
Recoveries	118	298
Balance	9,674	10,276
Real Estate | Commercial Real Estate Owner Occupied
Allowance for Loan Losses [Roll Forward]
Balance	4,064	4,192
Provision charged to expense	(139)	179
Losses charged off	(32)	(312)
Recoveries	17	5
Balance	3,910	4,064
Real Estate | Commercial Real Estate Investor Owned
Allowance for Loan Losses [Roll Forward]
Balance	8,640	10,403
Provision charged to expense	(2,273)	953
Losses charged off	(176)	(3,052)
Recoveries	24	336
Balance	6,215	8,640
Real Estate | Construction and Land Development
Allowance for Loan Losses [Roll Forward]
Balance	4,936	5,239
Provision charged to expense	(998)	(127)
Losses charged off	(144)	(190)
Recoveries	21	14
Balance	3,815	4,936
Real Estate | Residential Real Estate
Allowance for Loan Losses [Roll Forward]
Balance	2,111	2,026
Provision charged to expense	(299)	675
Losses charged off	0	(986)
Recoveries	34	396
Balance	1,846	2,111
Consumer & Other
Allowance for Loan Losses [Roll Forward]
Balance	43	31
Provision charged to expense	1	46
Losses charged off	0	(34)
Recoveries	0	0
Balance	44	43
Qualitative Adjustment
Allowance for Loan Losses [Roll Forward]
Balance	2,382	2,375
Provision charged to expense	(267)	7
Losses charged off	0	0
Recoveries	0	0
Balance	$ 2,115	$ 2,382