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Real Estate Investments - Gross Carrying Value of Operating Properties (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Property, Plant and Equipment, Gross [Abstract] |  |
Land | $ 487,209 | $ 486,068
Tenant improvements | 451,826 | 415,529
Operating properties | 4,030,605 | 3,951,719
Total | 4,030,605 | 3,951,719
Building and Improvements [Member] |  |
Property, Plant and Equipment, Gross [Abstract] |  |
Operating properties | $ 3,091,570 | $ 3,050,122

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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=119400593&loc=d3e572229-122910 + Details
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- Definition Amount before accumulated depletion of real estate held for productive use, excluding land held for sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 4 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6812-107765 + 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=119400593&loc=d3e572229-122910 + Details
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