Segment Information	9 Months Ended
Segment Information	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information Our primary business is the ownership and operation of office properties, and we currently have one reportable segment. Due to significant dispositions, during the fourth quarter of 2015, we changed the composition of our operating segments from two reportable segments (central business district properties and suburban properties) to one reportable segment. This change was made based on the financial information reviewed and used by the chief operating decision maker to make operating decisions, assess performance, develop strategy and allocate capital resources. More than 95% of our revenues for the nine months ended September 30, 2016 are from office properties.

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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