Income Taxes - (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Dividends paid to holders of common stock
Ordinary income	$ 0.01	$ 0.17	$ 0.00
Ordinary income, percentage	0.60%	17.90%	0.00%
Capital gains	$ 0.53	$ 0.13	$ 0.35
Capital gains, percentage	51.60%	13.90%	46.60%
Unrecaptured Section 1250 gain	$ 0.50	$ 0.66	$ 0.41
Unrecaptured Section 1250 gain, percentage	47.80%	68.20%	53.40%
Dividends declared per common share/unit	$ 1.04	$ 0.96	$ 0.76
Dividends declared per common share, percentage	100.00%	100.00%	100.00%