Stockholders' Equity - Narrative - Convertible Stock (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2009 shares
Class of Stock [Line Items]
Issuance of common stock	$ (3,339,202)	$ (663,896)	$ 0
Advisor [Member] | Convertible Stock [Member]
Class of Stock [Line Items]
Issuance of common stock (in shares) | shares	1,000			1,000
Aggregate percentage of cumulative, non-compounded, annual return on the original issue price added to total distributions qualifying for conversion of stock		8.00%
Convertible stock, conversion basis, multiplier	0.001
Convertible stock, percentage applied to the excess of enterprise value, including distributions to date		10.00%
Advisor [Member] | Advisor [Member] | Convertible Stock [Member]
Class of Stock [Line Items]
Convertible stock, redemption amount	$ 1