Equity method investment summarized financial information debt net.

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Financing Receivable, Extension Option Term

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Financing Receivable, Gain (Loss) On Sale Of Financing Receivable

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Financing Receivable, Repurchase Face Amount

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- Definition

Notes Receivable, Interest Rate

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- Definition

Amount, before allowance for credit loss, of financing receivable.

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- Definition

The number of real estate properties owned as of the balance sheet date.

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- Definition

The cash outflow from repayment of borrowings to finance the cost of construction.

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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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Debt and Preferred Equity Investments (Details)		3 Months Ended	12 Months Ended
Debt and Preferred Equity Investments (Details)	Dec. 31, 2020 USD ($) property	Sep. 30, 2021 USD ($) property	Dec. 31, 2018 USD ($)	Sep. 03, 2021 USD ($)
Summary of Investment Holdings [Line Items]
Number of real estate properties \| property		81
Austin Preferred Equity Investment \| Notes Receivable
Summary of Investment Holdings [Line Items]
Note receivable	$ 50,000,000
Number of real estate properties \| property	2
Notes receivable, interest rate	9.00%
Extension option term	1 year
Note receivable repurchased amount				$ 50,000,000
Gain on financing receivable redemption		$ 2,800,000
Brandywine 1919 Ventures
Summary of Investment Holdings [Line Items]
Note receivable			$ 44,400,000
Notes receivable, interest rate			4.00%
Debt, net			$ 44,400,000
Repayment of construction loan			$ 88,800,000