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Real Estate and Intangible Assets - Business Combinations and Asset Acquisitions (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018
Business Acquisition [Line Items] |  |
Total Purchase Price | $ 6,315 | $ 14,341
Customer relationships |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 196 | 566
Above market leases |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 23 | 49
Land |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 723 | 459
Building |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 4,541 | 11,609
Tenant Improvements |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 93 | 615
In-place leases |  |
Business Acquisition [Line Items] |  |
Assets Acquired | 432 | 509
Leasing costs |  |
Business Acquisition [Line Items] |  |
Assets Acquired | $ 307 | $ 534

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