Income Taxes - Summary of components of income tax expense (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$ 408,056us-gaap_CurrentFederalTaxExpenseBenefit	$ 400,931us-gaap_CurrentFederalTaxExpenseBenefit	$ 448,832us-gaap_CurrentFederalTaxExpenseBenefit
State	187,266	197,671	186,616
Total current	595,322us-gaap_CurrentIncomeTaxExpenseBenefit	598,602us-gaap_CurrentIncomeTaxExpenseBenefit	635,448us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred income (benefits) taxes:
Federal	(253,848)	(9,542)	(5,130)
State	(32,822)	44,795	43,489
Total deferred (benefits) taxes	(286,670)us-gaap_DeferredIncomeTaxExpenseBenefit	35,252us-gaap_DeferredIncomeTaxExpenseBenefit	38,359us-gaap_DeferredIncomeTaxExpenseBenefit
Income tax expense	$ 308,652us-gaap_IncomeTaxExpenseBenefit	$ 633,855us-gaap_IncomeTaxExpenseBenefit	$ 673,807us-gaap_IncomeTaxExpenseBenefit

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred state and local tax expense (benefit) pertaining to income (loss) from continuing operations.