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Loans and Investments - Narrative (Details) $ in Thousands | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Sep. 30, 2023 USD ($) loan | Jul. 31, 2022 USD ($) loan | Sep. 30, 2023 USD ($) loan | Jun. 30, 2023 USD ($) loan | Sep. 30, 2022 USD ($) loan | Jun. 30, 2022 USD ($) | Sep. 30, 2023 USD ($) loan borrower | Sep. 30, 2022 USD ($) loan | Dec. 31, 2022 USD ($) loan borrower | Dec. 31, 2021 USD ($)
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  |  |  | 723 |  | 747 |
Provision for credit losses |  |  | $ 15,015 |  | $ 965 |  | $ 51,510 | $ 9,055 |  |
Accrued interest receivable related to loans | $ 116,400 |  | $ 116,400 |  |  |  | $ 116,400 |  | $ 108,500 |
Number of loans for which no provision for loan loss made | loan | 0 |  | 0 |  |  |  | 0 |  | 0 |
Loans and investments, allowance for credit losses | $ 184,069 |  | $ 184,069 | $ 169,054 | $ 122,296 | $ 121,331 | $ 184,069 | 122,296 | $ 132,559 | $ 113,241
Interest income recognized on nonaccrual loans |  |  |  |  |  |  | 2,800 | $ 0 |  |
Multifamily bridge loan | $ 13,122,395 |  | $ 13,122,395 |  |  |  | 13,122,395 |  | 14,456,123 |
Interest reserve |  |  |  |  |  |  | $ 125,800 |  | 123,700 |
Loan modification, refinancing, and extensions | loan |  |  | 0 |  | 0 |  | 0 | 0 |  |
Number of loans sold | loan |  |  |  |  |  |  | 4 |  |  |
Bridge loans, total UPB |  |  |  |  |  |  | $ 293,055 |  | $ 157,960 |
Number of loans covered under interest reserve | loan | 516 |  | 516 |  |  |  | 516 |  | 480 |
Aggregate UPB covered under interest reserve | $ 8,310,000 |  | $ 8,310,000 |  |  |  | $ 8,310,000 |  | $ 7,700,000 |
Bridge loans |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  |  |  | 664 |  | 692 |
Multifamily bridge loan | $ 12,790,972 |  | $ 12,790,972 | $ 70,500 |  |  | $ 12,790,972 |  | $ 14,096,054 |
Variable rate, spread |  |  |  | 3.40% |  |  |  |  |  |
Financing receivable, fixed interest rate | 0.0300 |  |  |  |  |  |  |  |  |
Financing receivable, accrual rate | 0.0300 |  |  |  |  |  |  |  |  |
Financing receivable, total fixed rate | 0.0600 |  |  |  |  |  |  |  |  |
Financing receivable, borrower required funding | $ 10,500 |  |  |  |  |  |  |  |  |
Interest reserve | 2,500 |  |  |  |  |  |  |  |  |
Financing receivable, borrower requirement, capital improvements | $ 8,000 |  |  |  |  |  |  |  |  |
Number of loans sold | loan |  | 4 |  |  |  |  |  |  |  |
Bridge loans, total UPB |  | $ 296,900 |  | $ 182,000 |  |  | $ 217,400 |  |  |
Capital released |  | $ 78,000 |  |  |  |  |  |  |  |
Unrealized impairment loss |  |  |  |  |  | 2,000 |  |  |  |
Number of loans repurchased | loan |  |  |  | 2,000,000 |  |  |  |  |  |
Bridge Loan and Mezzanine Loan |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Bridge loan and mezzanine loans sold |  |  |  |  |  | 110,500 |  |  |  |
Loans, purchased with credit deterioration, discount |  |  |  |  |  | 102,200 |  |  |  |
Capital released |  |  |  |  |  | 66,300 |  |  |  |
Fees and expenses on mortgage loan |  |  |  |  |  | 9,200 |  |  |  |
Recovery of additional potential loan |  |  |  |  |  | 2,800 |  |  |  |
Six loans collateralized by a land development project |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans with unpaid principal balance | loan | 6 |  | 6 |  |  |  | 6 |  |  |
Unpaid principal balance on loans | $ 121,400 |  | $ 121,400 |  |  |  | $ 121,400 |  |  |
Five loans collateralized by a land development project |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans with unpaid principal balance | loan | 5 |  | 5 |  |  |  | 5 |  |  |
Unpaid principal balance on loans | $ 112,100 |  | $ 112,100 |  |  |  | $ 112,100 |  |  |
Weighted average accrual rate of interest (as a percent) |  |  |  |  |  |  | 7.91% |  |  |
Loans collateralized by a land development project |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Loans and investments, allowance for credit losses | 71,400 |  | 71,400 |  |  |  | $ 71,400 |  | $ 71,400 |
Non-performing loans |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  |  |  | 12 |  | 4 |
Carrying value of loans | 137,900 |  | 137,900 |  |  |  | $ 137,900 |  | $ 2,600 |
Loan loss reserves | 12,600 |  | 12,600 |  |  |  | 12,600 |  | 5,100 |
Bridge loans, total UPB |  |  |  |  |  |  | 157,862 |  | 7,750 |
Non-performing loans | Greater Than 90 Days Past Due |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Interest receivable | 0 |  | 0 |  |  |  | 0 |  | 0 |
Multifamily bridge loan | 35,015 |  | 35,015 |  |  |  | 35,015 |  | 7,750 |
Land |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Provision for credit losses |  |  | 60 |  | $ (8) |  | (106) | $ (60) |  |
Outstanding unfunded commitments | 1,080,000 |  | 1,080,000 |  |  |  | 1,080,000 |  | 1,150,000 |
Loans and investments, allowance for credit losses | 77,962 |  | 77,962 | $ 77,902 | $ 77,910 | $ 77,918 | 77,962 | $ 77,910 | 78,068 | $ 77,970
Bridge loans, total UPB |  |  |  |  |  |  | 134,215 |  | $ 134,215 |
Credit risk concentration |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Multifamily bridge loan | 13,122,395 |  | 13,122,395 |  |  |  | 13,122,395 |  |  |
Credit risk concentration | Land |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Multifamily bridge loan | $ 136,028 |  | $ 136,028 |  |  |  | $ 136,028 |  |  |
Total Assets | Credit risk concentration |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  |  |  | 92 |  | 38 |
Number of different borrowers | borrower |  |  |  |  |  |  | 5 |  | 5 |
Total Assets | Credit risk concentration | Five Borrowers |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Concentration risk, percentage |  |  |  |  |  |  | 12.00% |  | 11.00% |
Loans and investments portfolio | Credit risk concentration | Texas |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Concentration risk, percentage |  |  |  |  |  |  | 24.00% |  | 22.00% |
Loans and investments portfolio | Credit risk concentration | Florida |  |  |  |  |  |  |  |  |  |
Loans and Investments |  |  |  |  |  |  |  |  |  |
Concentration risk, percentage |  |  |  |  |  |  | 16.00% |  | 14.00% |

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