Investment in Real Estate (Details 4) (USD $)	3 Months Ended
	Mar. 31, 2012
One Industrial Property [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements	585,000
One Industrial Property [Member] | Discount Rate [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Unobservable Inputs	Discount Rate
Fair Value Measurements, Range, Maximum Percentage	11.75%
One Industrial Property [Member] | Market Rent Growth Rate [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Unobservable Inputs	Market Rent Growth rate
Fair Value Measurements, Range, Maximum Percentage	2.00%
One Industrial Property [Member] | Expense Growth Rate [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Unobservable Inputs	Expense Growth Rate
Fair Value Measurements, Range, Maximum Percentage	2.00%
One Industrial Property [Member] | Rental Rates [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Unobservable Inputs	Rental Rates Per Square Foot(A)
Fair Value Measurements, Range, Maximum	4,250
One Industrial Property [Member] | Future Exit Capitalization Rate [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Unobservable Inputs	Terminal Capitalization Rate
Fair Value Measurements, Range, Maximum Percentage	10.00%
Fourteen Industrial Properties [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements	36,175,000
Fair Value Measurements, Unobservable Inputs	(B)
3rd Party Pricing [Member] | Fourteen Industrial Properties [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Valuation Technique	3rd Party Pricing
Discounted Cash Flow [Member] | One Industrial Property [Member]
Quantitative information about the Level 3 fair value measurements
Fair Value Measurements, Valuation Technique	Discounted Cash Flow