Investment in Real Estate - Quantitative Information About Level 3 Fair Value Measurements (Details) $ in Thousands, ft² in Millions	Sep. 30, 2015 USD ($) ft² Property
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of industrial properties	629
Gross leasable area (GLA) of industrial properties owned | ft²	63.9
Unobservable Inputs (Level 3) | Contracted Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of industrial property | $	$ 17,850
Number of industrial properties	23
Gross leasable area (GLA) of industrial properties owned | ft²	0.7