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Debt and Preferred Equity Investments - Rollforward of Total Allowance for Loan Loss Reserves (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 USD ($) loan | Sep. 30, 2020 USD ($) | Sep. 30, 2021 USD ($) loan | Sep. 30, 2020 USD ($) | Dec. 31, 2020 USD ($)
Loan loss reserve activity |  |  |  |  |
Balance at beginning of year |  |  | $ 13,213,000 | $ 1,750,000 | $ 1,750,000
Current period provision for loan loss | $ 0 | $ 0 | 0 | 6,300,000 | 20,693,000
Write-offs charged against the allowance |  |  | (6,583,000) |  | (37,033,000)
Balance at end of period | $ 6,630,000 |  | $ 6,630,000 |  | 13,213,000
Number of financing receivables on non-accrual without allowance for loan loss | loan | 1 |  | 1 |  |
Financing receivable on non-accrual without allowance | $ 225,400,000 |  | $ 225,400,000 |  |
Investments Sold In 2020 |  |  |  |  |
Loan loss reserve activity |  |  |  |  |
Write-offs charged against the allowance |  |  | (300,000) |  | (19,000,000)
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Loan loss reserve activity |  |  |  |  |
Balance at beginning of year |  |  | $ 0 | $ 27,803,000 | 27,803,000
Balance at end of period |  |  |  |  | $ 0

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- Definition The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121581245&loc=d3e21338-158488 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of writeoff of financing receivable, charged against allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 + Details
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- Definition Amount of financing receivable on nonaccrual status with no allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447 + Details
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- Definition Amount of credit loss expense (reversal of expense) for financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(11)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
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