Risk Management and Use of Derivative Financial Instruments (Narratives) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Derivative
Total credit exposure	$ 4.8
Derivative in net liability position	3.6	$ 1.6
Termination value of assets	3.9	$ 1.7
Interest expense
Derivative
Estimated amount of derivative income loss to be reclassified to interest expense in the next 12 months	0.8
Other income
Derivative
Estimated amount of derivative income loss to be reclassified to interest expense in the next 12 months	1.1
Individual Counterparty
Derivative
Total credit exposure	$ 2.9