Covered Assets and FDIC Loss-sharing Asset Covered Assets and FDIC Loss-sharing Asset (Changes in Allowance for Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision (recapture) for loan and lease losses	$ 39,367	$ 5,752	$ 47,346
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year	4,944	6,055
Loans charged off	(5,112)	(1,488)
Recoveries	(4,332)	(2,025)
Provision (recapture) for loan and lease losses	25,892	(1,648)	6,055
Balance at the end of year	$ 30,056	$ 4,944	$ 6,055