Real Estate Investments - Assets Held for Sale (Details) $ in Millions	3 Months Ended
	Mar. 31, 2015 USD ($)	Jun. 30, 2015 property	Dec. 31, 2014 property
Acquisitions and Dispositions [Line Items]
Number of properties held for sale		3	2
Discontinued Operations [Member]
Acquisitions and Dispositions [Line Items]
Number of properties held for sale		2	2
Impairments related to property held for sale | $	$ 3.3