Real Estate - Schedule of Real Estate (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Acquisition And Disposition Of Properties And Discontinued Operations [Abstract]
Land	$ 777,991	$ 776,275
Buildings and improvements	2,889,285	2,848,781
Tenant improvements	211,588	191,046
Construction in progress	12,341	5,751
Right-of-use assets - finance leases	25,086	25,086
Total	3,916,291	3,846,939
Less: Accumulated depreciation and amortization	(647,718)	(586,800)
Operating real estate, net	3,268,573	3,260,139
Real estate under development	219,037	247,349	$ 253,402
Net investments in real estate	$ 3,487,610	$ 3,507,488

Acquisition and disposition of properties and discontinued operations.

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- Definition

Real estate investment property accumulated depreciation and amortization.

+ References

No definition available.

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

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-Publisher FASB
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- Definition

The current amount of expenditures for a real estate project that has not yet been completed.

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Amount, after accumulated amortization, of right-of-use asset from finance lease.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
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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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- Definition

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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Amount of real estate investments, 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; (7) other real estate investments; (8) real estate joint ventures; and (9) unconsolidated real estate and other joint ventures not separately presented.

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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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