Summary of Significant Accounting Policies (Income Tax) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
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	$ 43,300,000