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Real Estate and Intangible Assets - Components of Investments in Real Estate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real estate:
Land	$ 142,853	$ 137,532
Building and improvements	916,601	851,245
Tenant improvements	69,229	68,201
Accumulated depreciation	(228,468)	(207,523)
Total real estate, net	900,215	849,455
Land value subject to land lease agreements	4,436
Building and Improvements
Real Estate Properties [Line Items]
Depreciation	$ 36,000	$ 32,800	$ 29,900

X

- Definition

Land Subject to Land Lease Agreements, Value

+ References

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

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Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

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- Definition

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

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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, 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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Carrying amount as of the balance sheet date of improvements having a life longer than one year that were made for the benefit of one or more tenants.

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