Portfolio Loans Covered by Loss Share (Covered loans) - Summary of Covered Loans by Category (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Covered Loans [Line Items]
Loans Purchased From FDIC Outstanding Balance	$ 338,200,000	$ 496,200,000
Covered Loans
Covered Loans [Line Items]
Recorded Investment Covered Loans	221,433,000	300,610,000
Covered Loans | Real Estate Loans
Covered Loans [Line Items]
Recorded Investment Covered Loans	193,640,000	261,012,000
Covered Loans | Real Estate Loans | Construction and Land Development
Covered Loans [Line Items]
Weighted-Average Risk Rating	7.13	7.22
Recorded Investment Covered Loans	38,620,000	65,990,000
Covered Loans | Real Estate Loans | Commercial Real Estate Investor Owned
Covered Loans [Line Items]
Weighted-Average Risk Rating	6.00	6.12
Recorded Investment Covered Loans	64,287,000	75,093,000
Covered Loans | Real Estate Loans | Commercial Real Estate Owner Occupied
Covered Loans [Line Items]
Weighted-Average Risk Rating	6.60	6.03
Recorded Investment Covered Loans	44,307,000	63,101,000
Covered Loans | Real Estate Loans | Residential Real Estate
Covered Loans [Line Items]
Weighted-Average Risk Rating	5.67	4.81
Recorded Investment Covered Loans	46,426,000	56,828,000
Covered Loans | Commercial and industrial
Covered Loans [Line Items]
Weighted-Average Risk Rating	6.93	6.61
Recorded Investment Covered Loans	26,209,000	36,423,000
Covered Loans | Consumer & other
Covered Loans [Line Items]
Weighted-Average Risk Rating	4.33	4.14
Recorded Investment Covered Loans	$ 1,584,000	$ 3,175,000