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, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Taxes [Abstract]
Provision (benefit) for income taxes at statutory rate	$ 12,887,512	$ 7,241,517	$ 3,725,749
Percentage depletion	(1,466,456)	(1,059,303)	(846,040)
State income taxes, net of federal provision (benefit)	1,018,550	572,650	464,677
State net operating loss valuation allowance (release)			(31,000)
Other	(619,606)	(24,864)	(39,386)
Provision (benefit) for income taxes	$ 11,820,000	$ 6,730,000	$ 3,274,000