Commitments and Contingencies - Additional Information (Details) $ in Thousands, ft² in Millions	Jun. 30, 2018 USD ($) ft² Property
Other Commitments [Line Items]
Number of industrial properties | Property	471
Gross leasable area (GLA) of industrial properties | ft²	61.1
Development Activity
Other Commitments [Line Items]
Number of industrial properties | Property	5
Gross leasable area (GLA) of industrial properties | ft²	2.9
Estimated total investment | $	$ 186,000
Estimated total investment remaining to be funded | $	$ 79,100