Investments in Real Estate and Real Estate Under Construction - Summary of development arrangements outstanding (Details) ft² in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) ft²
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet | ft²	2,190
Expected Maximum Commitment/Contribution | $	$ 298,621
Joint Venture [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Ownership percentage	100.00%
Anderson, South Carolina [Member] | Industrial property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet | ft²	1,325
Expected Maximum Commitment/Contribution | $	$ 70,012
Lease Term (Years)	20 years
Lake Jackson, Texas [Member] | Office Building [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet | ft²	664
Expected Maximum Commitment/Contribution | $	$ 166,164
Lease Term (Years)	20 years
Charlotte, North Carolina [Member] | Office Building [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet | ft²	201
Expected Maximum Commitment/Contribution | $	$ 62,445
Lease Term (Years)	15 years