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Real Estate and Intangible Assets - Weighted Average Amortization Period for Intangible Assets and Liabilities (Details) | 6 Months Ended
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Jun. 30, 2019 | Jun. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 16 years 11 months 16 days | 11 years 1 month 6 days
In-place leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 15 years 6 months 15 days | 9 years 9 months 18 days
Leasing costs |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 15 years 6 months 15 days | 9 years 9 months 18 days
Customer relationships |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 20 years 5 months 27 days | 14 years 9 months 18 days
Above market leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 9 years 3 months 18 days | 9 years 9 months 18 days
Below Market Leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period | 7 years 9 months 15 days | 0 days

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- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
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