Allowance for Loan Losses - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructurings during the period			$ 0
Troubled debt restructurings, subsequently defaulted	0	0
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing allowance reduction in principal	366,000	366,000
Financing allowance reduction in interest payments	217,000	217,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing allowance reduction in interest payments	7,907,000	7,907,000
Financing allowance increase in principal	1,786,000	1,786,000
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing allowance reduction in principal	530,000	530,000
Financing allowance reduction in interest payments	$ 415,000	$ 415,000