Consolidated Statements of Shareholders' Equity - USD ($)		Common Stock [Member]	Series A Preferred Stock [Member]	Series B Preferred Stock [Member]	Series C Preferred Stock [Member]	Additional Paid in Capital [Member]	Undistributed Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance Beginning at Sep. 30, 2013		$ 444,885	$ 53,493,750	$ 57,500,000	$ 0	$ 222,487,068	$ 0	$ 1,989,268	$ 335,914,971
Shares Issued in Connection with the DRIP	[1]	42,961	0	0	0	38,047,373	0	0	38,090,334
Shares Issued in Connection with Underwritten Public Offering of Series C Preferred Stock, net of offering costs		80,500	0	0	0	65,032,186	0	0	65,112,686
Shares Issued Through the Exercise of Stock Options		1,642	0	0	0	1,325,527	0	0	1,327,169
Shares Issued Through Restricted Stock Awards		100	0	0	0	(100)	0	0	0
Stock Compensation Expense		0	0	0	0	347,002	0	0	347,002
Distributions To Common Shareholders		0	0	0	0	(18,293,168)	(11,238,262)	0	(29,531,430)
Net Income		0	0	0	0	0	19,845,294	0	19,845,294
Preferred Dividends		0	0	0	0	0	(8,607,032)	0	(8,607,032)
Unrealized Net Holding Loss on Securities Available for Sale, Net of Reclassification Adjustment		0	0	0	0	0	0	(1,867,912)	(1,867,912)
Balance Ending at Sep. 30, 2014		570,088	53,493,750	57,500,000	0	308,945,888	0	121,356	420,631,082
Shares Issued in Connection with the DRIP	[1]	49,755	0	0	0	48,354,801	0	0	48,404,556
Shares Issued Through the Exercise of Stock Options		812	0	0	0	611,598	0	0	612,410
Shares Issued Through Restricted Stock Awards		580	0	0	0	(580)	0	0	0
Stock Compensation Expense		0	0	0	0	448,895	0	0	448,895
Distributions To Common Shareholders		0	0	0	0	(18,523,344)	(16,998,783)	0	(35,522,127)
Net Income		0	0	0	0	0	25,605,815	0	25,605,815
Preferred Dividends		0	0	0	0	0	(8,607,032)	0	(8,607,032)
Unrealized Net Holding Loss on Securities Available for Sale, Net of Reclassification Adjustment		0	0	0	0	0	0	(5,562,959)	(5,562,959)
Balance Ending at Sep. 30, 2015		621,235	53,493,750	57,500,000	0	339,837,258	0	(5,441,603)	446,010,640
Shares Issued in Connection with the DRIP	[1]	65,157	0	0	0	72,110,640	0	0	72,175,797
Shares Issued in Connection with Underwritten Public Offering of Series C Preferred Stock, net of offering costs		0	0	0	135,000,000	(4,456,578)	0	0	130,543,422
Shares Issued Through the Exercise of Stock Options		2,450	0	0	0	1,880,850	0	0	1,883,300
Shares Issued Through Restricted Stock Awards		400	0	0	0	(400)	0	0	0
Stock Compensation Expense		0	0	0	0	926,465	0	0	926,465
Distributions To Common Shareholders		0	0	0	0	(21,502,295)	(20,531,888)	0	(42,034,183)
Net Income		0	0	0	0	0	32,494,507	0	32,494,507
Preferred Dividends		0	0	0	0	0	(9,020,470)	0	(9,020,470)
Unrealized Net Holding Loss on Securities Available for Sale, Net of Reclassification Adjustment		0	0	0	0	0	0	18,383,870	18,383,870
Preferred Stock Called for Redemption		0	(53,493,750)	0	0	2,930,649	(2,942,149)	0	(53,505,250)
Cancellation of Shares Related to Forfeiture of Restricted Stock Awards		(32)	0	0	0	32	0	0	0
Balance Ending at Sep. 30, 2016		$ 689,210	$ 0	$ 57,500,000	$ 135,000,000	$ 391,726,621	$ 0	$ 12,942,267	$ 597,858,098

[1] (1) Dividend Reinvestment and Stock Purchase Plan