Equity - Distributions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Distributions Per Share
Total distributions paid (usd per share)	$ 0.6500	$ 0.6500	$ 0.6500
Ordinary income
Distributions Per Share
Total distributions paid (usd per share)	0.3091	0.1994	0.3220
Return of capital
Distributions Per Share
Total distributions paid (usd per share)	0.3409	0.1403	0.3280
Capital gain
Distributions Per Share
Total distributions paid (usd per share)	$ 0.0000	$ 0.3103	$ 0.0000