Allowance for Credit Losses - Summary of Activity in Allowance for Loan Losses (Parenthetical) (Detail) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Covered loans charge-offs	$ 749		$ 749	$ 146
Covered loans recovered	462		462
Loans charged-off	4,751	8,356	18,990	20,075
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	1,340	1,441	9,954	8,766
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	2,032	4,389	6,522	6,382
Non-Performing Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	4,800
Non-Performing Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	$ 3,500