Covered Assets and FDIC Loss-sharing Asset (FDIC Loss-sharing Asset) (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
Balance at beginning of period	$ 140,003	$ 175,071	$ 205,991	$ 209,694
Established through acquisitions	0	0	68,734	0
Cash received from the FDIC	(14,881)	(49,194)	(51,000)	(6,108)
FDIC reimbursable losses, net	(494)	587	2,192	1,138
Amortization, net	(9,694)	(33,418)	(32,556)	(10,928)
Impairment	(3,193)	18,705	2,424	921
Sale of other real estate	(1,315)	(4,881)	(3,487)	(1,471)
Write-downs of other real estate	1,141	4,503	911	467
Other	110	304	660	156
Balance at end of period	$ 111,677	$ 111,677	$ 193,869	$ 111,677