Income Taxes - Federal Statutory Rate to Pre-Tax Income from Continuing Operations (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Tax expense at statutory rate of 34%	$ 2,737,798	$ 2,616,860
State income tax, net of Federal tax expense	272,491	296,676
Amortization of deferred investment tax credits	(5,265)	(5,265)
Adjustment to tax return filed	40,914
Other	(12,082)	655
Total income tax expense	3,033,856	2,908,926
Discontinued operations	10,729	(11,034)
Income tax expense from continuing operations	$ 3,044,585	$ 2,897,892