| Property Portfolio - Summary of the carrying amount of intangible assets and liabilities (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018 | 
|---|---|---|
| Assets | ||
| Cost | $ 65,498 | $ 43,152 | 
| Accumulated Amortization | (11,489) | (6,864) | 
| Net | 54,009 | 36,288 | 
| Liabilities | ||
| Cost | 3,855 | 2,336 | 
| Accumulated Amortization | (568) | (308) | 
| Net | 3,287 | 2,028 | 
| In-place leases [Member] | ||
| Assets | ||
| Cost | 34,697 | 21,753 | 
| Accumulated Amortization | (6,599) | (4,037) | 
| Net | 28,098 | 17,716 | 
| Above Market Ground Lease [Member] | ||
| Assets | ||
| Cost | 707 | |
| Accumulated Amortization | (28) | |
| Net | 679 | |
| Above Market Lease intangibles [Member] | ||
| Assets | ||
| Cost | 12,236 | 8,009 | 
| Accumulated Amortization | (1,991) | (1,096) | 
| Net | 10,245 | 6,913 | 
| Leasing Costs [Member] | ||
| Assets | ||
| Cost | 18,565 | 12,683 | 
| Accumulated Amortization | (2,899) | (1,703) | 
| Net | $ 15,666 | $ 10,980 | 
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- References No definition available. 
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- Definition Amount of accumulated amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. No definition available. 
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- Definition Amount before amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. No definition available. 
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- Definition Amount after amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. No definition available. 
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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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