Income Taxes (Summary of Distributions Paid) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common Shares, Ordinary income, Amount	$ 0.097500	$ 0.117000	$ 0.455000
Common Shares, Return of capital, Amount	0.877500	0.468000
Common Shares, Total, Amount	$ 0.975000	$ 0.585000	$ 0.455000
Common Shares, Ordinary income, Percent	10.00%	20.00%	100.00%
Common Shares, Return of capital, Percent	90.00%	80.00%
Common Shares, Total, Percent	100.00%	100.00%	100.00%
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares, Ordinary income, Amount			$ 1.649124
Preferred Shares, Total, Amount			$ 1.649124
Preferred Shares, Ordinary income, Percent			100.00%
Preferred Shares, Total, Percent			100.00%
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares, Ordinary income, Amount		$ 0.104160	$ 0.494792
Preferred Shares, Total, Amount		$ 0.104160	$ 0.494792
Preferred Shares, Ordinary income, Percent		100.00%	100.00%
Preferred Shares, Total, Percent		100.00%	100.00%
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares, Ordinary income, Amount	$ 0.625000	$ 0.522569
Preferred Shares, Total, Amount	$ 0.625000	$ 0.522569
Preferred Shares, Ordinary income, Percent	100.00%	100.00%	0.00%
Preferred Shares, Total, Percent	100.00%	100.00%	0.00%