Income Taxes - Federal Income Tax Treatment of Common Dividends (Details) - Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Ordinary Income	$ 0.6552	$ 0.6935	$ 0.2629
Unrecaptured Section 1250 Gain	0.1627	0.1130	0.1241
Capital Gain	0.0648	0.0066	0.0000
Nondividend Distribution - Return of Capital	0.0000	0.0272	0.0000
Distributions Per Common Share	$ 0.8827	$ 0.8403	$ 0.3870
Ordinary Income as a Percentage of Distribution	74.23%	82.53%	67.93%
Unrecaptured Section 1250 Gain as a Percentage of Distribution	18.43%	13.45%	32.07%
Capital Gain as Percentage of Distributions	7.34%	0.78%	0.00%
Nondivided Distribution - Return of Capital As Percentage Of Distributions	0.00%	3.24%	0.00%
Common Distributions Percentage	100.00%	100.00%	100.00%