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Summary of Significant Accounting Policies - Construction in Progress (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
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Property, Plant and Equipment [Line Items] |  |
Construction in progress | $ 139,285 | $ 91,114
Glebe Road |  |
Property, Plant and Equipment [Line Items] |  |
Construction in progress | 117,156 | 83,462
Ashbrook Marketplace |  |
Property, Plant and Equipment [Line Items] |  |
Construction in progress | 9,519 | 0
Other |  |
Property, Plant and Equipment [Line Items] |  |
Construction in progress | $ 12,610 | $ 7,652

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- Definition The current amount of expenditures for a real estate project that has not yet been completed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.10) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition 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. + References No definition available. + Details
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