Covered Assets and FDIC Loss-sharing Asset (Changes in Allowance for Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended		15 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Provision for loan and lease losses		$ 34,506	$ 4,962
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Beginning balance	31,784	4,944	6,055	7,948
Loans charged off	(977)	(2,574)	(368)	(312)
Recoveries	2,342	3,406	328	258
Provision for loan and lease losses	(3,992)	23,381	2,312	433
Ending balance	$ 29,157	$ 29,157	$ 8,327	$ 29,157