Changes in FDIC Loss-Share Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Balance, beginning of the period	$ 59,741	$ 80,179	$ 74,390	$ 89,359
Discount accretion of the present value at the acquisition dates	82	146	244	437
Effect of additional cash flows on covered loans (prospective recognition)	(2,091)	(2,889)	(5,959)	(8,167)
Increase due to impairment on covered loans				16,932
Other reimbursable expenses	1,619	1,166	4,173	2,787
Reimbursements from the FDIC	(7,413)		(14,950)	(22,746)
Other			(5,960)
Balance, end of the period	$ 51,938	$ 78,602	$ 51,938	$ 78,602