Investments in Real Estate and Real Estate Under Construction Summary of acquisitions and build-to-suit transactions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	$ 79,555
Land and Land Estate	4,305
Building and Improvements	62,302
Lease in-place Value	12,948
Industrial Property [Member] | Rantoul Illinois [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	41,277
Land and Land Estate	1,304
Building and Improvements	32,562
Lease in-place Value	7,411
Office Property [Member] | Parachute Colorado [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	13,928
Land and Land Estate	1,400
Building and Improvements	10,751
Lease in-place Value	1,777
Office Property [Member] | Rock Hill South Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	24,350
Land and Land Estate	1,601
Building and Improvements	18,989
Lease in-place Value	$ 3,760