Distributions (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Distributions
Minimum distribution of taxable income (as a percent)									90.00%
Ordinary taxable distribution									$ 1.534	$ 1.539	$ 1.370
Return of capital									$ 0.313	$ 0.242	$ 0.295
Unrecaptured Section 1250 gain									$ 0.058	$ 0.004
Long term capital gain										$ 0.005	$ 0.015
Total	$ 0.510	$ 0.465	$ 0.465	$ 0.465	$ 0.465	$ 0.455	$ 0.435	$ 0.435	$ 1.905	$ 1.79	$ 1.68