Covered Assets and FDIC Loss-sharing Asset (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
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	$ 3,400,000		$ 3,400,000
Provision for loan and lease losses			35,623,000	4,029,000
Federal deposit insurance corporation loss-sharing indemnified assets	120,300,000		120,300,000
Federal deposit insurance corporation loss-sharing indemnified assets receivable	19,800,000		19,800,000
FDIC Loss-sharing Asset, Period Increase (Decrease)	21,900,000
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Percentage of loss shared by FDIC	80.00%		80.00%
FDIC Percentage Of Loss Recoveries	80.00%		80.00%
Percentage of loss shared by FDIC When Loss Share Thresholds Met	95.00%		95.00%
Percentage Of Loss Recoveries Shared By FDIC When Loss Share Thresholds Met	95.00%		95.00%
Provision for loan and lease losses	11,688,000	2,301,000	27,373,000	1,879,000
Impairment expenses			28,300,000
Negative provision to adjust allowance for loss			$ 900,000
Covered Loans [Member] | Maximum [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loss Sharing Agreement Effective Years			10 years
Loss Recovery Provision Effective Years			10 years
Covered Loans [Member] | Minimum [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loss Sharing Agreement Effective Years			5 years
Loss Recovery Provision Effective Years			8 years