Commitments and Contingencies	9 Months Ended
Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies General As of September 30, 2018, we had commitments of approximately $776.5 million, excluding our ground lease commitments, for contracts and executed leases directly related to our operating properties and development projects. Environmental Matters We follow the policy of monitoring all of our properties, both acquisition and existing stabilized portfolio properties, for the presence of hazardous or toxic substances. While there can be no assurance that a material environmental liability does not exist, we are not currently aware of any environmental liability with respect to our stabilized portfolio properties that would have a material adverse effect on our financial condition, results of operations and cash flow, or that we believe would require additional disclosure or the recording of a loss contingency. As of September 30, 2018, we had accrued environmental remediation liabilities of approximately $79.6 million recorded on our consolidated balance sheets in connection with certain of our in-process and future development projects. The accrued environmental remediation liabilities represent the remaining costs we estimate we will incur when we commence development at various development acquisition sites. These estimates, which we developed with the assistance of third party experts, consist primarily of the removal of contaminated soil and other related costs since we are required to dispose of any existing contaminated soil when we develop new properties at these sites. We record estimated environmental remediation obligations for acquired properties at the acquisition date when we are aware of such costs and when such costs are probable of being incurred and can be reasonably estimated. Estimated costs related to development environmental remediation liabilities are recorded as an increase to the cost of the development project. Actual costs are recorded as a decrease to the liability when incurred. These accruals are adjusted as an increase or decrease to the development project costs and as an increase or decrease to the accrued environmental remediation liability if we obtain further information or circumstances change. The environmental remediation obligation recorded at September 30, 2018 was not discounted to its present value since we expect to complete the remediation activities in the next one to five years in connection with development activities at the various sites. It is possible that we could incur additional environmental remediation costs in connection with these future development projects. However, given we are in the pre-development phase on these future development projects, potential additional environmental costs cannot be reasonably estimated at this time and certain changes in estimates could occur as the site conditions, final project timing, design elements, actual soil conditions and other aspects of the projects, which may depend upon municipal and other approvals beyond the control of the Company, are determined. Other than the accrued environmental liabilities discussed above, we are not aware of any unasserted claims and assessments with respect to an environmental liability that we believe would require additional disclosure or the recording of an additional loss contingency.

Commitments and Contingencies

General

As of September 30, 2018, we had commitments of approximately $776.5 million, excluding our ground lease commitments, for contracts and executed leases directly related to our operating properties and development projects.

Environmental Matters

We follow the policy of monitoring all of our properties, both acquisition and existing stabilized portfolio properties, for the presence of hazardous or toxic substances. While there can be no assurance that a material environmental liability does not exist, we are not currently aware of any environmental liability with respect to our stabilized portfolio properties that would have a material adverse effect on our financial condition, results of operations and cash flow, or that we believe would require additional disclosure or the recording of a loss contingency.

As of September 30, 2018, we had accrued environmental remediation liabilities of approximately $79.6 million recorded on our consolidated balance sheets in connection with certain of our in-process and future development projects. The accrued environmental remediation liabilities represent the remaining costs we estimate we will incur when we commence development at various development acquisition sites. These estimates, which we developed with the assistance of third party experts, consist primarily of the removal of contaminated soil and other related costs since we are required to dispose of any existing contaminated soil when we develop new properties at these sites.

We record estimated environmental remediation obligations for acquired properties at the acquisition date when we are aware of such costs and when such costs are probable of being incurred and can be reasonably estimated. Estimated costs related to development environmental remediation liabilities are recorded as an increase to the cost of the development project. Actual costs are recorded as a decrease to the liability when incurred. These accruals are adjusted as an increase or decrease to the development project costs and as an increase or decrease to the accrued environmental remediation liability if we obtain further information or circumstances change. The environmental remediation obligation recorded at September 30, 2018 was not discounted to its present value since we expect to complete the remediation activities in the next one to five years in connection with development activities at the various sites. It is possible that we could incur additional environmental remediation costs in connection with these future development projects. However, given we are in the pre-development phase on these future development projects, potential additional environmental costs cannot be reasonably estimated at this time and certain changes in estimates could occur as the site conditions, final project timing, design elements, actual soil conditions and other aspects of the projects, which may depend upon municipal and other approvals beyond the control of the Company, are determined.

Other than the accrued environmental liabilities discussed above, we are not aware of any unasserted claims and assessments with respect to an environmental liability that we believe would require additional disclosure or the recording of an additional loss contingency.