Stockholders' Equity - Narrative - Distributions Declared (Details) - USD ($)				3 Months Ended								12 Months Ended
	May 02, 2018	Mar. 20, 2018	Mar. 13, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common share, distribution rate per share per day, declared (in dollars per share)			$ 0.00151890410958904		$ 0.001519	$ 0.001683	$ 0.001964
Distributions declared												$ 121,054,857	$ 54,339,823	$ 54,828,267
Distributions payable				$ 3,515,310				$ 4,595,301				$ 3,515,310	$ 4,595,301
Distributions declared per common share (in dollars per share)				$ 0.140	0.140	$ 1.153	0.177	$ 0.181	$ 0.181	$ 0.179	$ 0.177	$ 1.610	$ 0.718
Common Stock [Member]
Class of Stock [Line Items]
Common share, distribution rate per share per day, declared (in dollars per share)					$ 0.001519		$ 0.001964
Common stock, distribution rate, percentage		6.00%			6.00%	6.00%	7.00%
Share price (in dollars per share)			$ 9.24	$ 9.24		$ 10.24	$ 10.24					$ 9.24
Distributions declared												$ 121,054,857	$ 54,339,823
Distributions payable				$ 3,515,310				$ 4,595,301				$ 3,515,310	$ 4,595,301
Dividend Paid [Member]
Class of Stock [Line Items]
Distributions declared per common share (in dollars per share)	$ 1.00
Distributions paid, common stock, including distribution reinvestment plan	$ 75,298,163