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, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 1,987,166	$ 1,897,074
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,023	10,429
90 or More Days Past Due	11,911	20,446
Total Past Due	13,934	30,875
Current	1,973,232	1,866,199
Total	1,987,144	1,897,412
Total	1,987,166	1,897,074
Non-Covered Loans | Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	704	4,521
90 or More Days Past Due	862	792
Total Past Due	1,566	5,313
Current	878,828	757,889
Total	880,394	763,202
Non-Covered Loans | Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,095,056	1,122,751
Non-Covered Loans | Real Estate | Commercial - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	1,945
90 or More Days Past Due	344	1,522
Total Past Due	344	3,467
Current	325,035	330,949
Total	325,379	334,416
Non-Covered Loans | Real Estate | Commercial - Investor Owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	15	2,308
90 or More Days Past Due	4,509	4,209
Total Past Due	4,524	6,517
Current	471,977	470,637
Total	476,501	477,154
Non-Covered Loans | Real Estate | Construction and Land Development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	596	1,356
90 or More Days Past Due	5,306	9,786
Total Past Due	5,902	11,142
Current	140,334	129,005
Total	146,236	140,147
Non-Covered Loans | Real Estate | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	703	299
90 or More Days Past Due	890	4,137
Total Past Due	1,593	4,436
Current	145,347	166,598
Total	146,940	171,034
Non-Covered Loans | Consumer & Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	5	0
90 or More Days Past Due	0	0
Total Past Due	5	0
Current	11,711	11,121
Total	11,694	11,459
Total	$ 11,716	$ 11,121