Activity in Allowance for Loan Losses Related to ASC 310-30 Acquired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Covered Under Loss Sharing Agreements With F D I C [Member]	Dec. 31, 2013 Covered Under Loss Sharing Agreements With F D I C [Member]	Mar. 31, 2014 Covered Under Loss Sharing Agreements With F D I C [Member] A S C Subtopic 31030 [Member]	Mar. 31, 2013 Covered Under Loss Sharing Agreements With F D I C [Member] A S C Subtopic 31030 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 640,555	$ 730,607	$ 97,773	$ 102,092	$ 93,915	$ 95,407
Provision for loan losses	73,072	223,856			24,555	14,041
Charge-offs	(112,773)	(138,385)			(28,099)	(17,875)
Recoveries	39,494	30,433
Net write-down related to loans sold	0	(163,143)
Balance at end of period	$ 640,348	$ 683,368	$ 97,773	$ 102,092	$ 90,371	$ 91,573