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	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,085,872	$ 2,106,039
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	5,032	3,217
90 or More Days Past Due	16,191	8,278
Total Past Due	21,223	11,495
Current	2,064,649	2,094,544
Total	2,085,428	2,106,028
Total	2,085,872	2,106,039
Non-Covered Loans | Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,414	14
90 or More Days Past Due	0	0
Total Past Due	1,414	14
Current	947,757	962,870
Total	949,171	962,884
Non-Covered Loans | Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,116,538	1,126,178
Non-Covered Loans | Real Estate | Commercial - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,018	1,352
90 or More Days Past Due	1,307	2,081
Total Past Due	3,325	3,433
Current	335,761	329,809
Total	339,086	333,242
Non-Covered Loans | Real Estate | Commercial - Investor Owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,179	0
90 or More Days Past Due	11,678	4,045
Total Past Due	12,857	4,045
Current	460,146	482,422
Total	473,003	486,467
Non-Covered Loans | Real Estate | Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	343	1,201
90 or More Days Past Due	2,524	1,559
Total Past Due	2,867	2,760
Current	153,354	158,151
Total	156,221	160,911
Non-Covered Loans | Real Estate | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	78	616
90 or More Days Past Due	682	593
Total Past Due	760	1,209
Current	147,468	144,349
Total	148,228	145,558
Non-Covered Loans | Consumer & Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	34
90 or More Days Past Due	0	0
Total Past Due	0	34
Current	20,163	16,943
Total	19,719	16,966
Total	$ 20,163	$ 16,977