Allowance for Credit Losses - Summary of Activity in Allowance for Loan Losses (Parenthetical) (Detail) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	$ 14,239	$ 11,719
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	8,614	7,325
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans charged-off	4,490	1,993
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