Stockholders' Equity (Tax Status of Distributions) (Details) - Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Total Distributions Per Share (in usd per share)	$ 0.255000	$ 0.240000	$ 2.853075
Unrecaptured Section 1250 Gain (in usd per share)	0.000000	0.070522	0.100934
Nondividend Distributions (in usd per share)	0.000000	0.000000	2.190636
AMT Adjustment (in usd per share)	0.000000	0.017756	0.000000
Ordinary Dividends
Class of Stock [Line Items]
Total Distributions Per Share (in usd per share)	0.251396	0.093312	0.079661
Long-Term Capital Gain
Class of Stock [Line Items]
Total Distributions Per Share (in usd per share)	$ 0.003604	$ 0.146688	$ 0.582778