Shareholders' Equity (Details Narrative) - USD ($)			6 Months Ended
	Oct. 02, 2017	Jun. 29, 2017	Mar. 31, 2018	Mar. 31, 2017	Jan. 16, 2018	Sep. 30, 2017
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares authorized			192,039,750			192,039,750
Common stock, shares issued			78,846,177			75,630,521
Common stock, shares outstanding			78,846,177			75,630,521
Excess stock, shares authorized			200,000,000			200,000,000
Excess Stock, par value			$ 0.01			$ 0.01
Excess Stock , shares issued
Excess Stock , shares outstanding
Amount of dividend reinvested			$ 6,045,930	$ 4,536,751
Board of Directors [Member] | April 2, 2018 [Member]
Subsidiary or Equity Method Investee [Line Items]
Dividend declared per share			$ 0.17
Dividend Reinvestment and Stock Purchase Plan [Member]
Subsidiary or Equity Method Investee [Line Items]
Common stock issued under plan			3,161,320
Preferred Stock ATM Program [Member]
Subsidiary or Equity Method Investee [Line Items]
Cumulative redeemable preferred, stock dividend rate		6.125%
Preferred stock redemption price		$ 25.00
Maximum proceeds from issuance of sale of equity		$ 100,000,000
Number of preferred stock shares sold			1,255,931
Weighted average exercise price per share			$ 25.09
Net proceeds from offering			$ 30,942,000
Maximum [Member]
Subsidiary or Equity Method Investee [Line Items]
Share Repurchase Program authorizes amount					$ 10,000,000
Common Stock [Member]
Subsidiary or Equity Method Investee [Line Items]
Percentage increase in common stock dividend	6.25%
Dividend declared per share			$ 0.17
Common stock dividend, description	Board of Directors approved a 6.25% increase in our quarterly common stock dividend, raising it to $0.17 per share from $0.16 per share, representing our second dividend increase in three years.
Increase in dividend period	3 years
Dividend increase percentage	13.00%
Annualized dividend rate per share price	$ 0.68
Period of maintained or increased its cash dividend	26 years
Cash raised from issuance of common stock under DRIP			$ 49,042,921
Amount of dividend reinvested			6,045,930
Cash dividends paid			$ 26,319,599
Common Stock [Member] | Maximum [Member]
Subsidiary or Equity Method Investee [Line Items]
Dividend declared per share	$ 0.17
Common Stock [Member] | Minimum [Member]
Subsidiary or Equity Method Investee [Line Items]
Dividend declared per share	$ 0.16
Series C Preferred Stock [Member]
Subsidiary or Equity Method Investee [Line Items]
Preferred stock, shares authorized			12,400,000			12,400,000
Cumulative redeemable preferred, stock dividend rate			6.125%			6.125%
Preferred stock, par value			$ 0.01			$ 0.01
Preferred stock, shares issued			11,095,376			9,839,445
Preferred stock, shares outstanding			11,095,376			9,839,445
Series C Preferred Stock [Member] | Board of Directors [Member] | April 2, 2018 [Member]
Subsidiary or Equity Method Investee [Line Items]
Cumulative redeemable preferred, stock dividend rate			6.125%
Dividend declared per share			$ 0.3828125
Series C Cumulative Redeemable Preferred Stock [Member]
Subsidiary or Equity Method Investee [Line Items]
Cumulative redeemable preferred, stock dividend rate			6.125%
Preferred stock, shares issued			11,095,376
Preferred stock, shares outstanding			11,095,376
Dividend declared per share			$ 0.765625
Cash dividends paid			$ 8,301,342
Accrued dividend			$ 1,415,816
Annual rate of dividends cumulative and payable			$ 1.53125
Preferred stock redemption price			$ 25.00