Impaired Loans and Valuation Allowance for Loan Losses - Troubled Debt Restructurings Defaulted (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	3
Recorded Investment	$ 2,017
Construction and Land Development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Recorded Investment	0
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2
Recorded Investment	397
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Recorded Investment	1,620
Commercial and Financial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Recorded Investment	0
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Recorded Investment	$ 0