Distributions - Summary of Payment of Dividends to Preferred Shareholders (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends Payable [Line Items]
Declaration Date	Jan. 25, 2018
Record Date	Mar. 15, 2018
Payment Date	Feb. 15, 2018
Preferred stock, dividend declared per share, paid	$ (0.52)		$ (0.51)	$ (0.32)
Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Amount of distributions paid for preferred stock	$ 5,667,441		$ 7,556,588	$ 7,556,588
Preferred stock, dividend declared per share, paid	$ 1.546875		$ 2.0625	$ 2.0625
Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Amount of distributions paid for preferred stock	$ 7,602,400		$ 7,007,057
Preferred stock, dividend declared per share, paid	$ 2.00		$ 2.22466
Series C Preferred Stock [Member]
Dividends Payable [Line Items]
Amount of distributions paid for preferred stock	$ 3,396,094
Preferred stock, dividend declared per share, paid	$ 0.590625
Dividend Payment Date One [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Jan. 19, 2017
Record Date	Feb. 15, 2017
Payment Date	Mar. 15, 2017
Amount of distributions paid for preferred stock	$ 1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625
Dividend Payment Date One [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Jan. 19, 2017
Record Date	Feb. 15, 2017
Payment Date	Mar. 15, 2017
Dividend Payment Date One [Member] | Series C Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Jul. 03, 2017
Record Date	Aug. 15, 2017
Payment Date	Sep. 15, 2017
Amount of distributions paid for preferred stock	$ 970,313
Preferred stock, dividend declared per share, paid	$ 0.168750
Dividend Payment Date Two [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Apr. 03, 2017
Record Date	May 15, 2017
Payment Date	Jun. 15, 2017
Amount of distributions paid for preferred stock	$ 1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625
Dividend Payment Date Two [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Apr. 03, 2017
Record Date	May 15, 2017
Payment Date	Jun. 15, 2017
Dividend Payment Date Two [Member] | Series C Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Oct. 02, 2017
Record Date	Nov. 15, 2017
Payment Date	Dec. 15, 2017
Amount of distributions paid for preferred stock	$ 2,425,781
Preferred stock, dividend declared per share, paid	$ 0.421875
Dividend Payment Date Three [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date		Jul. 03, 2017
Record Date		Aug. 15, 2017
Payment Date		Sep. 15, 2017
Amount of distributions paid for preferred stock		$ 1,889,147
Preferred stock, dividend declared per share, paid		$ 0.515625
Dividend Payment Date Three [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Jul. 03, 2017
Record Date	Aug. 15, 2017
Payment Date	Sep. 15, 2017
Dividend Payment Date Four [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Jan. 15, 2016
Record Date			Feb. 16, 2016
Payment Date			Mar. 15, 2016
Amount of distributions paid for preferred stock			$ 1,889,147
Preferred stock, dividend declared per share, paid			$ 0.515625
Dividend Payment Date Four [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date	Oct. 02, 2017
Record Date	Nov. 15, 2017
Payment Date	Dec. 15, 2017
Dividend Payment Date Five [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Apr. 04, 2016
Record Date			May 16, 2016
Payment Date			Jun. 15, 2016
Amount of distributions paid for preferred stock			$ 1,889,147
Preferred stock, dividend declared per share, paid			$ 0.515625
Dividend Payment Date Five [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Jan. 15, 2016
Record Date			Feb. 16, 2016
Payment Date			Mar. 15, 2016
Amount of distributions paid for preferred stock			$ 1,305,257
Preferred stock, dividend declared per share, paid			$ 0.72466
Dividend Payment Date Six [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Jul. 01, 2016
Record Date			Aug. 15, 2016
Payment Date			Sep. 15, 2016
Amount of distributions paid for preferred stock			$ 1,889,147
Preferred stock, dividend declared per share, paid			$ 0.515625
Dividend Payment Date Six [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Apr. 04, 2016
Record Date			May 16, 2016
Payment Date			Jun. 15, 2016
Amount of distributions paid for preferred stock			$ 1,900,600
Preferred stock, dividend declared per share, paid			$ 0.50
Dividend Payment Date Seven [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Oct. 03, 2016
Record Date			Nov. 17, 2016
Payment Date			Dec. 15, 2016
Amount of distributions paid for preferred stock			$ 1,889,147
Preferred stock, dividend declared per share, paid			$ 0.515625
Dividend Payment Date Seven [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Jul. 01, 2016
Record Date			Aug. 15, 2016
Payment Date			Sep. 15, 2016
Amount of distributions paid for preferred stock			$ 1,900,600
Preferred stock, dividend declared per share, paid			$ 0.50
Dividend Payment Date Eight [Member] | Series A Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date				Jan. 15, 2015
Record Date				Feb. 17, 2015
Payment Date				Mar. 16, 2015
Amount of distributions paid for preferred stock				$ 1,889,147
Preferred stock, dividend declared per share, paid				$ 0.515625
Dividend Payment Date Eight [Member] | Series B Preferred Stock [Member]
Dividends Payable [Line Items]
Declaration Date			Oct. 03, 2016
Record Date			Nov. 17, 2016
Payment Date			Dec. 15, 2016
Amount of distributions paid for preferred stock			$ 1,900,600
Preferred stock, dividend declared per share, paid			$ 0.50