Summary of Significant Accounting Policies (Income Tax) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Accounting Policies [Abstract]
Percentage of annual REIT taxable income distributed to stockholders	100.00%
REIT income tax expense	$ 0
Deferred income tax expense (benefit)	0	$ 0
Valuation allowance decrease	$ 24,300,000