Covered Assets and FDIC Loss-sharing Asset (Changes in Allowance for Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Provision for loan and lease losses	$ (20)	$ 20,185
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Beginning balance	30,056	4,944
Loans charged off	(2,382)	(562)
Recoveries	835	437
Provision for loan and lease losses	980	15,685
Ending balance	$ 29,489	$ 20,504