Loans and Allowance for Loan Losses - Summary of Composition of Total TDRs (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$ 41,373	$ 41,623
Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	9,899	10,220
Non-Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	21,797	18,698
Non-Accrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$ 9,677	$ 12,705