Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands		Common Stock [Member]	Preferred Stock [Member] Preferred Stock Series C [Member]	Additional Paid-in Capital [Member]	Undistributed Income Loss [Member]	AOCI Attributable to Parent [Member]	Total
Beginning balance, value at Sep. 30, 2020		$ 981	$ 471,994	$ 568,998	$ 0	$ (4,368)	$ 1,037,605
Shares Issued in Connection with the DRIP (1)	[1]	1	0	1,257	0	0	1,258
Shares Issued in Connection with At-The-Market Sales Agreement Program of 6.125% Series C Preferred Stock, net of offering costs		0	77,646	(1,688)	0	0	75,958
Stock Compensation Expense		0	0	57	0	0	57
Distributions To Common Shareholders		0	0	9,075	(25,746)	0	(16,671)
Stock Option Exercise		1	0	1,565	0	0	1,566
Net Income Attributable to Shareholders		0	0	0	33,916	0	33,916
Preferred Dividends ($0.3828125 per share)		0	0	0	(8,170)	0	(8,170)
Change in Fair Value of Interest Rate Swap Agreement		0	0	0	0	433	433
Ending balance, value at Dec. 31, 2020		983	549,640	579,264	0	(3,935)	1,125,952
Beginning balance, value at Sep. 30, 2021		983	549,640	546,341	0	(2,230)	1,094,734
Shares Issued in Connection with the DRIP (1)	[1]	0	0	3	0	0	3
Stock Compensation Expense		0	0	94	0	0	94
Distributions To Common Shareholders		0	0	(6,284)	(11,417)	0	(17,701)
Stock Option Exercise		1	0	662	0	0	663
Shares Withheld for Employee Taxes in Connection with the Net Exercise of Employee Stock Options		1	0	(1,557)	0	0	(1,556)
Net Income Attributable to Shareholders		0	0	0	19,833	0	19,833
Preferred Dividends ($0.3828125 per share)		0	0	0	(8,416)	0	(8,416)
Change in Fair Value of Interest Rate Swap Agreement		0	0	0	0	1,118	1,118
Ending balance, value at Dec. 31, 2021		$ 985	$ 549,640	$ 539,259	$ 0	$ (1,112)	$ 1,088,772

[1] Dividend Reinvestment and Stock Purchase Plan