Loans - Changes in FDIC Loss-Share Receivable (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Balance, beginning of the period	$ 74,390	$ 89,359
Discount accretion of the present value at the acquisition dates	325	582
Effect of additional cash flows on covered loans (prospective recognition)	(7,767)	(10,592)
Increase due to impairment on covered loans		19,520
Other reimbursable expenses	5,467	3,893
Reimbursements from the FDIC	(21,935)	(28,372)
Other	(5,484)
Balance, end of the period	$ 44,996	$ 74,390