Covered Assets and FDIC Loss-sharing Asset (FDIC Loss-sharing Asset) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Covered Assets And FDIC Loss Sharing Asset
Balance at beginning of period	$ 159,061		$ 193,053	$ 175,071	$ 205,991
Established through acquisitions	0	68,734		0	68,734
Cash received from the FDIC	(19,508)		(44,892)	(34,313)	(44,892)
FDIC reimbursable losses, net	618		(782)	1,081	1,054
Amortization, net	(9,851)		(8,059)	(23,725)	(21,628)
Impairment	9,350		1,841	21,898	1,503
Sale of other real estate	(1,498)		(1,149)	(3,565)	(2,016)
Write-downs of other real estate	1,732		443	3,362	443
Other	99		505	194	505
Balance at end of period	$ 140,003	$ 209,694	$ 209,694	$ 140,003	$ 209,694