Risk Management and Use of Derivative Financial Instruments (Narratives) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Concentration Risk
Collateral posted for derivative positions	$ 0		$ 0
Unrealized loss recognized in OCI	1,298,000	$ 1,731,000
Amounts reported in OCI related to interest rate swaps to be reclassified to interest expense	900,000
Total credit exposure on derivatives	100,000
Derivatives in net liability position, fair value	200,000		800,000
Potential loss on contract termination for default	200,000		$ 800,000
Noncontrolling Interest
Concentration Risk
Amounts reported in OCI related to interest rate swaps to be reclassified to interest expense	100,000
Individual Counterparty
Concentration Risk
Total credit exposure on derivatives	100,000
Interest expense
Concentration Risk
Loss reclassified outside of OCI	$ 275,000	$ 404,000