Portfolio Loans Not Covered by Loss Share ("Non-covered") - Summary of Aging of Recorded Investment in Past Due Non-covered Loans by Portfolio Class and Category (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,110,825	$ 2,106,039
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,915	3,217
90 or More Days Past Due	10,899	8,278
Total Past Due	12,814	11,495
Current	2,098,011	2,094,544
Total	2,109,943	2,106,028
Total	2,110,825	2,106,039
Non-Covered Loans | Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	445	14
90 or More Days Past Due	1,337	0
Total Past Due	1,782	14
Current	1,005,616	962,870
Total	1,007,398	962,884
Non-Covered Loans | Commercial Real Estate Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	442	1,352
90 or More Days Past Due	190	2,081
Total Past Due	632	3,433
Current	350,021	329,809
Total	350,653	333,242
Non-Covered Loans | Commercial Real Estate Investor Owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,025	0
90 or More Days Past Due	6,842	4,045
Total Past Due	7,867	4,045
Current	443,235	482,422
Total	451,102	486,467
Non-Covered Loans | Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	1,201
90 or More Days Past Due	2,210	1,559
Total Past Due	2,210	2,760
Current	112,398	158,151
Total	114,608	160,911
Non-Covered Loans | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	616
90 or More Days Past Due	320	593
Total Past Due	320	1,209
Current	150,000	144,349
Total	150,320	145,558
Non-Covered Loans | Consumer & Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	3	34
90 or More Days Past Due	0	0
Total Past Due	3	34
Current	36,741	16,943
Total	35,862	16,966
Total	$ 36,744	$ 16,977