Summary of Investments in Real Estate (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Real Estate Properties [Line Items]
Land	$ 203,130	$ 193,026
Building	1,313,805	1,279,777
Furniture, fixtures and equipment	55,080	31,353
Total investment in real estate	1,572,015	1,504,156
Accumulated depreciation	(101,589)	(84,097)
Investments in real estate, net	$ 1,470,426	$ 1,420,059
Building
Real Estate Properties [Line Items]
Depreciable Lives	40 years
Furniture, fixtures and equipment \| Minimum
Real Estate Properties [Line Items]
Depreciable Lives	5 years
Furniture, fixtures and equipment \| Maximum
Real Estate Properties [Line Items]
Depreciable Lives	10 years

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount before accumulated depreciation of fixtures and equipment. Includes, but is not limited to, machinery, equipment, and engines.

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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The cumulative amount of depreciation for real estate property held for investment purposes.

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Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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