Risk Management and Use of Derivative Financial Instruments (Details 7)	3 Months Ended
	Mar. 31, 2014
Retail Industry
Concentration Risk
Concentration Risk Percentage	22.00%
Electronics Industry
Concentration Risk
Concentration Risk Percentage	10.00%
All other Industry
Concentration Risk
Concentration Risk Percentage	68.00%
Industrial
Concentration Risk
Concentration Risk Percentage	26.00%
Office
Concentration Risk
Concentration Risk Percentage	25.00%
Warehouse/Distribution
Concentration Risk
Concentration Risk Percentage	19.00%
Retail
Concentration Risk
Concentration Risk Percentage	15.00%
All Other
Concentration Risk
Concentration Risk Percentage	15.00%
US
Concentration Risk
Concentration Risk Percentage	66.00%
International
Concentration Risk
Concentration Risk Percentage	34.00%
Europe
Concentration Risk
Concentration Risk Percentage	33.00%
Germany
Concentration Risk
Concentration Risk Percentage	12.00%
Other Europe
Concentration Risk
Concentration Risk Percentage	21.00%
Other International
Concentration Risk
Concentration Risk Percentage	1.00%