Portfolio Loans Covered by Loss Share (Covered loans) - Summary of Covered Loans by Category (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Covered Loans	Dec. 31, 2012 Covered Loans	Mar. 31, 2013 Covered Loans Real Estate Loans	Dec. 31, 2012 Covered Loans Real Estate Loans	Mar. 31, 2013 Covered Loans Real Estate Loans Construction and Land Development	Dec. 31, 2012 Covered Loans Real Estate Loans Construction and Land Development rating	Sep. 30, 2012 Covered Loans Real Estate Loans Construction and Land Development rating	Mar. 31, 2013 Covered Loans Real Estate Loans Commercial Real Estate Investor Owned	Dec. 31, 2012 Covered Loans Real Estate Loans Commercial Real Estate Investor Owned rating	Sep. 30, 2012 Covered Loans Real Estate Loans Commercial Real Estate Investor Owned rating	Mar. 31, 2013 Covered Loans Real Estate Loans Commercial Real Estate Owner Occupied	Dec. 31, 2012 Covered Loans Real Estate Loans Commercial Real Estate Owner Occupied rating	Sep. 30, 2012 Covered Loans Real Estate Loans Commercial Real Estate Owner Occupied rating	Mar. 31, 2013 Covered Loans Real Estate Loans Residential Real Estate	Dec. 31, 2012 Covered Loans Real Estate Loans Residential Real Estate rating	Sep. 30, 2012 Covered Loans Real Estate Loans Residential Real Estate rating	Mar. 31, 2013 Covered Loans Commercial and industrial	Dec. 31, 2012 Covered Loans Commercial and industrial rating	Sep. 30, 2012 Covered Loans Commercial and industrial rating	Mar. 31, 2013 Covered Loans Consumer & other	Dec. 31, 2012 Covered Loans Consumer & other rating	Sep. 30, 2012 Covered Loans Consumer & other rating
Covered Loans [Line Items]
Net cash proceeds received from FDIC loss share receivable	$ 1,685	$ 11,614
Weighted-Average Risk Rating								7.06	7.13		6.08	6.42		6.65	6.73		5.68	5.75		6.57	6.78		4.19	4.34
Recorded Investment Covered Loans			$ 182,822	$ 201,118	$ 167,904	$ 177,810	$ 27,026	$ 30,537		$ 54,401	$ 57,602		$ 45,973	$ 47,140		$ 40,504	$ 42,531		$ 13,790	$ 22,034		$ 1,128	$ 1,274