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Real Estate and Intangible Assets - Fair Value of Acquired Assets and Liabilities Assumed (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Business Acquisition [Line Items] |  |
Discount on Assumed Debt | $ 0 | $ 399
Total Purchase Price | 63,245 | 132,157
Customer Relationships |  |
Business Acquisition [Line Items] |  |
Purchase Price | 2,698 | 10,806
Above Market Leases |  |
Business Acquisition [Line Items] |  |
Purchase Price | 239 | 3,824
Below Market Leases |  |
Business Acquisition [Line Items] |  |
Fair Value of Interest Rate Swap Assumed and (Below Market Leases) | 1,475 | 2,101
Land |  |
Business Acquisition [Line Items] |  |
Purchase Price | 6,278 | 21,509
Building |  |
Business Acquisition [Line Items] |  |
Purchase Price | 44,754 | 68,617
Tenant Improvements |  |
Business Acquisition [Line Items] |  |
Purchase Price | 2,400 | 9,977
In-Place Leases |  |
Business Acquisition [Line Items] |  |
Purchase Price | 4,418 | 12,018
Leasing Costs |  |
Business Acquisition [Line Items] |  |
Purchase Price | 3,933 | 7,066
Interest rate swaps |  |
Business Acquisition [Line Items] |  |
Fair Value of Interest Rate Swap Assumed and (Below Market Leases) | $ 0 | $ 42

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