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, 2011	Dec. 31, 2010	Dec. 31, 2009
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision (recapture) for loan and lease losses	$ 5,752	$ 47,346	$ 63,500
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year	6,055	0
Loans charged off	(1,488)	0
Recoveries	(2,025)	0
Provision (recapture) for loan and lease losses	(1,648)	6,055	0
Balance at the end of year	$ 4,944	$ 6,055	$ 0