Risk Management and Use of Derivative Financial Instruments (Narratives) (Details) (USD $)							9 Months Ended
	Sep. 30, 2012 quantity	Dec. 31, 2011	Sep. 30, 2012 Derivatives Not in Cash Flow Hedging Relationships	Sep. 30, 2012 Derivatives Not in Cash Flow Hedging Relationships Noncontrolling Interest	Sep. 30, 2012 Cash Flow Hedging	Sep. 30, 2012 Cash Flow Hedging Jointly Owned Investments	Sep. 30, 2012 Forward contracts	Sep. 30, 2012 3-Month LIBOR Cash Flow Hedging Noncontrolling Interest Jointly Owned Investments	Sep. 30, 2012 1-Month LIBOR Cash Flow Hedging Noncontrolling Interest Jointly Owned Investments	Sep. 30, 2012 CPA 16 - Global quantity	Sep. 30, 2012 CPA 15
Summary of Derivative Instruments
Notional Amount				$ 43,600,000
Fair Value			(16,627,000)	(4,000,000)	(6,071,000)	3,000
Debt instrument interest rate at end of period								3.00%	4.20%
Stock warrants											1,600,000
Derivative instruments gain loss reclassification from OCI to income, to be transferred							2,000,000
Maximum credit exposure	100,000
Aggregate termination value of derivatives in liability position	25,600,000
Percentage geography										18.20%
Assets	4,782,495,000	1,462,623,000								3,400,000,000
Number of real estate properties	430									503
Number of tenants	133									145
Derivative Fair Value, Gross Liability	$ 24,100,000