Other Data (Details 1) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Characterization of distributions on common stock
Ordinary income per share	$ 0.75	$ 0.42	$ 0.78
Return of capital per share	0.33	0.50	0.35
Unrecaptured section 1250 gain per share	0.12	0.28	0.07
Common stock distributions per share	$ 1.20	$ 1.20	$ 1.20
Ordinary income in percent of common stock distribution	62.20%	34.50%	65.00%
Return of capital in percent of common stock distribution	27.80%	42.00%	29.50%
Unrecaptured section 1250 gain in percent of common stock distribution	10.00%	23.50%	5.50%
Common stock distribution in percentage	100.00%	100.00%	100.00%