Distributions (Details) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Distributions
Minimum distribution of taxable income (as a percent)									90.00%
Ordinary taxable distribution									$ 1.690	$ 1.474	$ 1.534
Return of capital									0.357	0.196	0.313
Unrecaptured Section 1250 gain									0.023	0.370	0.058
Total	$ 0.54	$ 0.51	$ 0.51	$ 0.51	$ 0.51	$ 0.51	$ 0.51	$ 0.51	$ 2.070	$ 2.040	$ 1.905