Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Income Taxes [Line Items]
Income before income taxes	$ 3,243,249	$ 6,033,703			$ 8,641,354	$ 9,655,771
Income tax provision	417,827	1,494,516			1,538,829	2,778,348
Effective tax rate					17.80%
Expected effective tax rate	24.23%				24.23%		25.69%
Discrete items recognized			298,000
Reversed of deferred tax asset valuation allowance				3,021,000
Maximum
Income Taxes [Line Items]
Net operating loss and business tax credit carry forwards expiration date					At various dates through December 2031
Available to Reduce Future Federal Income Taxes
Income Taxes [Line Items]
Net operating loss carry forwards	37,633,000				37,633,000
Business tax credit carry forwards	$ 1,520,000				$ 1,520,000