Other Data (Details 1) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Characterization of distributions on common stock
Ordinary income per share	$ 0.78	$ 0.61	$ 0.50
Return of capital per share	0.35	0.08	0.70
Unrecaptured section 1250 gain per share	0.07	0.51	0.00
Common stock distributions per share	$ 1.2	$ 1.2	$ 1.2
Ordinary income in percent of common stock distribution	65.00%	51.00%	42.00%
Return of capital in percent of common stock distribution	29.50%	6.70%	58.00%
Unrecaptured section 1250 gain in percent of common stock distribution	5.50%	42.30%	0.00%
Common stock distribution in percentage	100.00%	100.00%	100.00%