Federal Home Loan Bank Advances - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Federal Home Loan Bank advances	$ 45,000,000	$ 35,000,000
Start date of maturities	2017-03	2017-03
End date of maturities	2017-09	2017-09
Average rate of interest maturities	1.34%	1.35%
Borrowing line of credit facility	150,000,000
Available borrowing capacity under line of credit	$ 94,000,000
Minimum [Member]
Line of Credit Facility [Line Items]
Fixed rate of interest on maturities	1.22%	1.22%
Maximum [Member]
Line of Credit Facility [Line Items]
Fixed rate of interest on maturities	1.51%	1.51%