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Debt and Preferred Equity Investments - Narrative (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2020 USD ($) | Sep. 30, 2020 USD ($) segment | Dec. 31, 2019 USD ($) segment | Jan. 01, 2020 USD ($) | Dec. 31, 2018 USD ($)
Preferred equity investment |  |  |  |  |
Carrying Value | $ 1,153,363,000 | $ 1,153,363,000 | $ 1,580,306,000 |  |
Recorded investment, nonaccrual status | $ 27,700,000 | $ 27,700,000 |  |  |
Weighted average risk rating | 1.4 | 1.4 |  |  |
Number of portfolio segments of financial receivables (segment) | segment |  | 1 | 1 |  |
Additional amount of financing receivables included in other assets | $ 110,900,000 | $ 110,900,000 | $ 131,100,000 |  |
Provision for loan losses | 0.0 | 6,300,000 |  |  |
Allowance for loan and lease losses, real estate | 19,010,000 | 19,010,000 | 1,750,000 |  | $ 5,750,000
Financing Receivables, Equal to Greater than 90 Days Past Due |  |  |  |  |
Preferred equity investment |  |  |  |  |
Recorded investment, past due | 0 | 0 | 0 |  |
Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |
Preferred equity investment |  |  |  |  |
Additional amount of financing receivables included in other assets |  |  |  | $ 11,400,000 |
Allowance for loan and lease losses, real estate |  |  | 27,804,000 |  | $ 0
Total floating rate |  |  |  |  |
Preferred equity investment |  |  |  |  |
Carrying Value | 439,084,000 | 439,084,000 | $ 841,660,000 |  |
Total floating rate | Mortgage/Mezzanine Loan Due March 2020 |  |  |  |  |
Preferred equity investment |  |  |  |  |
Carrying Value | $ 25,300,000 | $ 25,300,000 |  |  |

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