Loans and Allowance for Loan Losses - Allowance for Loan Losses by Portfolio Segment and Related Recorded Investment in Loans (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision expense for impairment covered loans	$ 7,569	$ 8,101	$ 25,404	$ 26,141
Allowance for loan losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision expense for impairment covered loans			(25,404)	(26,141)
Allowance for loan losses [Member] | Covered loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision expense for impairment covered loans			$ 7,987	$ 2,645