Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Parenthetical) (Details) - property	Mar. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Number of Properties	121
Cira Square [Member] \| Held for Sale Properties Included in Continuing Operations [Member]
Segment Reporting Information [Line Items]
Number of Properties		58