Covered Assets and FDIC Loss-sharing Asset (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Payment Of Clawback If Losses Less Than Stated Levels, Period After Acquisition	10 years 45 days
Amount of estimated clawback liability	$ 3,600,000	$ 3,700,000
Provision (recapture) for loan and lease losses	39,367,000	5,752,000	47,346,000
Federal deposit insurance corporation loss-sharing indemnified assets	87,700,000	157,500,000
Federal deposit insurance corporation loss-sharing indemnified assets receivable	8,600,000	17,600,000
Maximum [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loss Recovery Provision Effective Years	10 years
Loss Sharing Agreement Effective Years	10 years
Minimum [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loss Recovery Provision Effective Years	8 years
Loss Sharing Agreement Effective Years	5 years
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Percentage of loss shared by FDIC When Loss Share Thresholds Met		95.00%
Percentage of loss shared by FDIC	80.00%
FDIC Percentage Of Loss Recoveries	80.00%	95.00%
Provision (recapture) for loan and lease losses	25,892,000	(1,648,000)	6,055,000
Impairment expenses	29,400,000
Negative provision to adjust allowance for loss	$ 3,500,000