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Real Estate Investments - Gross Carrying Value of Operating Properties (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Property, Plant and Equipment, Gross [Abstract] |  |
Land | $ 509,503 | $ 508,363
Tenant improvements | 438,121 | 415,529
Operating properties | 4,015,879 | 3,953,319
Total | 4,015,879 | 3,953,319
Building and Improvements [Member] |  |
Property, Plant and Equipment, Gross [Abstract] |  |
Operating properties | $ 3,068,255 | $ 3,029,427

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- Definition Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Carrying amount as of the balance sheet date of improvements having a life longer than one year that were made for the benefit of one or more tenants. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(f)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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