Income Taxes (Summary of Difference Between Provision (Benefit) for Income Taxes and Amount which Would Result from Application of Federal Statutory Rate) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes at statutory rate	$ 1,477,327	$ (6,299,259)	$ 4,955,069
Percentage depletion	(570,801)	(395,649)	(530,783)
State income taxes, net of federal provision (benefit)	3,900	(683,800)	487,500
Effect of graduated rates	85,644	(86,745)	(62,922)
Restricted stock tax benefit	(238,000)
Deferred directors compensation benefit	(79,000)
Other	9,930	(245,547)	(12,864)
Provision (benefit) for income taxes	$ 689,000	$ (7,711,000)	$ 4,836,000