Risk Management and Use of Derivative Financial Instruments (Narratives) (Details) (USD $)			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Interest rate swap	Sep. 30, 2013 Interest rate swap Noncontrolling interest	Sep. 30, 2013 Foreign currency contract	Sep. 30, 2013 Interest rate cap	Sep. 30, 2013 Interest rate cap Noncontrolling interest	Sep. 30, 2013 Embedded derivatives	Sep. 30, 2013 Maximum Interest rate cap Noncontrolling interest
Risk Management and Use of Deriviative Financial Instruments
Total credit exposure on derivatives	$ 2,700,000
Total credit exposure on derivatives to a single counterparty	1,900,000
Derivative Instrument Detail
Estimated amount reclassified from OCI to income, derivatives			7,100,000	600,000	1,100,000
Derivatives, net liability position	22,500,000	23,000,000
Aggregate termination value for immediate settlement	24,100,000	25,100,000
Foreign currency exchange rate	1.3525	1.3218						1.278
Footnote Details
Derivative fair value	(12,311,000)								100,000
Derivative notional amount							$ 52,500,000
Cap rate						4.00%
Debt, interest rate at period end						2.77%