Investments in Real Estate and Real Estate Under Construction Summary of development arrangements outstanding (Details) (USD $)	6 Months Ended
	Jun. 30, 2013 sqft
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square feet of property	1,163,000
Expected Maximum Commitment/Contribution	$ 98,600,000
Rantoul Illinois [Member] | Industrial Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square feet of property	813,000
Expected Maximum Commitment/Contribution	42,600,000
Lease Term (Years)	20 years
Bingen, Washington [Member] | Industrial Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square feet of property	124,000
Expected Maximum Commitment/Contribution	18,900,000
Lease Term (Years)	12 years
Las Vegas, Nevada [Member] | Industrial Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square feet of property	180,000	[1]
Expected Maximum Commitment/Contribution	29,600,000	[1]
Lease Term (Years)	20 years	[1]
Costs incurred related to development arrangement	1,191,000
Albany, Georgia [Member] | Retail Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square feet of property	46,000
Expected Maximum Commitment/Contribution	$ 7,500,000
Lease Term (Years)	15 years

[1] At June 30, 2013, the Company's commitment could have been terminated by the Company due to an outstanding contingency, thus costs incurred through June 30, 2013 of $1,191 are recognized as pre-development costs and included in “Other assets” in the accompanying unaudited condensed consolidated balance sheet. Subsequent to June 30, 2013, the termination right expired.