Organization and Basis of Presentation (Details)	Jun. 30, 2011
Summary of stabilized portfolio of operating properties
Number of Buildings	8
Stabilized Portfolio [Member]
Summary of stabilized portfolio of operating properties
Number of Buildings	147
Rentable square feet	15,071,228
Number of Tenants	478
Percentage Occupied	90.20%
Stabilized Portfolio [Member] | Industrial Properties [Member]
Summary of stabilized portfolio of operating properties
Number of Buildings	40
Rentable square feet	3,605,407
Number of Tenants	62
Percentage Occupied	97.60%
Stabilized Portfolio [Member] | Office Properties [Member]
Summary of stabilized portfolio of operating properties
Number of Buildings	107
Rentable square feet	11,465,821
Number of Tenants	416
Percentage Occupied	87.90%
Office Properties [Member]
Summary of stabilized portfolio of operating properties
Number of Buildings	8