Taxes (Details 1) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Summary of reconciliation between cash dividends paid and dividends paid deduction
Cash dividends paid	$ 23,339,255	$ 21,161,033	$ 18,466,225
Less: Portion designated capital (gains) losses distribution	(5,100,437)	(2,908,322)	(1,175,321)
Less: Return of capital	(5,569,549)	(5,403,932)	(6,118,373)
Estimated dividends paid deduction	$ 12,669,269	$ 12,848,779	$ 11,172,531