Allowance for Loan Losses - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Condition for considering loan as past due	If the required principal and interest payments have not been received as of the date such payments were due
Condition for considering loan as non-accrual	When the loan is more than three payments past due, as well as when required by regulatory provisions
Condition for considering loan as impaired	Once it has gone over three payments or 90 days delinquent
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