Loans - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Troubled Debt Restructurings [Member]	Sep. 30, 2013 Troubled Debt Restructurings [Member]	Sep. 30, 2014 Troubled Debt Restructurings [Member]	Sep. 30, 2013 Troubled Debt Restructurings [Member]	Sep. 30, 2014 Troubled Debt Restructurings with Subsequent Default [Member]	Sep. 30, 2014 Troubled Debt Restructurings with Subsequent Default [Member]	Dec. 31, 2013 Troubled Debt Restructurings with Subsequent Default [Member]	Sep. 30, 2014 Majority [Member]	Sep. 30, 2014 Maximum [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Term of loan commitments												60 days	36 months
Increment in allowance for loan losses					$ 59,000	$ 206,000	$ 175,000	$ 778,000
Amounts charged off	667,000	1,104,000	3,023,000	7,854,000	70,000	0	73,000	1,800,000	0	0	0
Effect of troubled debt restructurings on provision for loan losses									$ 0	$ 0	$ 0
Maximum period after which troubled debt restructuring is considered to be in payment by default			30 days
Period of cumulative homogeneous loans past due included in company analysis			90 days