Loans - Changes in FDIC Loss-Share Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Receivables [Abstract]
Balance, beginning of the period	$ 43,413	$ 69,928	$ 44,996	$ 74,390
Discount accretion of the present value at the acquisition dates	32	81	65	162
Effect of additional cash flows on covered loans (prospective recognition)	(3,467)	(2,231)	(4,949)	(3,868)
Decrease in the provision for losses on covered loans	(105)		(2,783)
Other reimbursable expenses	1,540	1,088	2,492	2,554
(Reimbursements from) payments to the FDIC	(727)	(3,165)	865	(7,537)
Other		(5,960)		(5,960)
Balance, end of the period	$ 40,686	$ 59,741	$ 40,686	$ 59,741