Allowance for Loan Losses - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Minimum period of valuation and adjustment of nonperforming and non-homogeneous collateral dependent loan	30 days
Maximum period of valuation and adjustment of nonperforming and non-homogeneous collateral dependent loan	180 days
Delinquent period of homogeneous loans monitored	More than 60 days
Minimum [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Principal and interest amounts contractually due brought current period	6 months
Impaired Loans, Number of days for which the amount is due	90 days
Number of days past due following modification in a Troubled Debt Restructuring	60 days