Summary of Significant Accounting Policies (Income Taxes) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Percent distribution of REIT taxable income	100.00%
Income provision	$ 0
Number of years subequent to a failed REIT Qualifing Test the Company would not be Qualified as a REIT	4 years
Uncertain tax positions	$ 0
Penalties and interest	0	$ 0	$ 0
Penalties and interest accrued	0	0
Federal income tax basis	6,500,000,000	$ 7,600,000,000
Taxable REIT Subsidiary [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	30,800,000
Valuation allowance	$ 30,800,000
Expiration dates	Jan. 01, 2018