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Agreements and Transactions with Related Parties - Other Related Party (Details) | 1 Months Ended | 12 Months Ended | 24 Months Ended |
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Dec. 31, 2021 USD ($) shares | Oct. 31, 2021 USD ($) | Mar. 31, 2021 USD ($) | Jan. 31, 2021 | Dec. 31, 2020 USD ($) | Oct. 31, 2020 USD ($) | Aug. 31, 2020 USD ($) | Mar. 31, 2020 USD ($) property | Sep. 30, 2019 USD ($) | Jan. 31, 2019 USD ($) | Dec. 31, 2021 USD ($) shares | Dec. 31, 2020 USD ($) shares | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) property loan | Dec. 31, 2017 USD ($) loan property | Dec. 31, 2016 USD ($) property | Dec. 31, 2015 USD ($) | Dec. 31, 2021 USD ($) shares | Jul. 31, 2019 USD ($)
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Due to related party | $ 26,570,000 |  |  |  | $ 2,365,000 |  |  |  |  |  | $ 26,570,000 | $ 2,365,000 |  |  |  |  |  | $ 26,570,000 |
Due from related parties | 84,318,000 |  |  |  | 12,449,000 |  |  |  |  |  | 84,318,000 | 12,449,000 |  |  |  |  |  | 84,318,000 |
Related party financing | 0 |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  | 0 |
Interest expense on related party loan |  |  |  |  |  |  |  |  |  |  | 200,000 |  |  |  |  |  |  |  |
Outstanding principal balance of related party financing | 0 |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  | 0 |
Proceeds from Bridge loan on a multi family property |  | $ 67,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Entitled to annual fee | $ 1,300,000 |  |  |  | 1,600,000 |  |  |  |  |  | 1,300,000 | 1,600,000 |  |  |  |  |  | $ 1,300,000 |
Paydowns of principal made by borrower |  |  |  |  |  |  |  |  |  |  | 2,516,771,000 | 1,243,694,000 | $ 1,753,693,000 |  |  |  |  |  |
Base spread (as a percent) |  | 3.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment made |  |  |  |  |  |  |  |  |  |  | $ 9,209,475,000 | 2,376,233,000 | 2,712,354,000 |  |  |  |  |  |
Proceeds from repayment in full |  |  |  |  |  |  |  |  |  | $ 10,900,000 |  |  |  |  |  |  |  |  |
Indirect ownership percentage |  |  |  |  |  |  |  |  |  |  | 9.20% |  |  |  |  |  |  |  |
(Income) loss from equity affiliates |  |  |  |  |  |  |  |  |  |  | $ (34,567,000) | (76,161,000) | (10,635,000) |  |  |  |  |  |
Percentage of our Former Manager's outstanding membership interest of related party in another related party | 35.00% |  |  |  |  |  |  |  |  |  | 35.00% |  |  |  |  |  |  | 35.00% |
Other Related Party Transactions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Due from related parties | $ 84,300,000 |  |  |  | 12,400,000 |  |  |  |  |  | $ 84,300,000 | 12,400,000 |  |  |  |  |  | $ 84,300,000 |
CMBS/Conduit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans assumed | $ 26,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Chairman and Chief executive officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reimbursement for flights chartered by the company's executives |  |  |  |  |  |  |  |  |  |  | $ 200,000 |  |  |  |  |  |  |  |
Ownership interest limit of our common stock under company charter (as a percent) | 5.00% |  |  |  |  |  |  |  |  |  | 5.00% |  |  |  |  |  |  | 5.00% |
ACM Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distribution received |  |  |  |  |  |  |  |  |  |  | $ 28,000,000.0 | 43,200,000 |  |  |  |  |  |  |
Retail property |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property purchased | $ 32,500,000 |  |  |  |  |  |  |  |  |  | 32,500,000 |  |  |  |  |  |  | $ 32,500,000 |
Maturity date of March 2030 | Private Label | Lexford Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  | $ 34,600,000 |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  | 3.30% |  |  |  |  |  |  |  |  |  |  |
Preferred equity investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity investment | 8,200,000 |  |  |  |  |  |  |  |  |  | 8,200,000 |  |  |  |  |  |  | 8,200,000 |
Preferred equity investments | Single-Family Rental |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment made |  |  |  |  |  | $ 4,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Bridge Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount | 35,000,000.0 |  |  |  |  |  |  |  |  |  | 35,000,000.0 |  |  |  |  |  |  | 35,000,000.0 |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |
Bridge Loans | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.50% |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.25% |  |  |
Bridge Loans | Single-Family Rental |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loan committed |  |  |  |  | 32,500,000 | $ 30,500,000 |  |  |  |  | 3,200,000 |  |  |  |  |  |  |  |
Investment made |  |  |  |  | $ 3,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bridge Loan Several Multifamily Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 37,500,000 |  |  |  |  |
Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of January 2021 [Member] | Chairman and Chief executive officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | 600,000 | 600,000 |  |  |  |  |  |
Bridge Loan Six Multifamily Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
UPB converted to a mezzanine loan |  |  |  |  |  |  |  |  |  | 2,000,000.0 |  |  |  |  |  |  |  |  |
Bridge Loan Six Multifamily Properties [Member] | Maturity Date September 2019 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  | 12,900,000 |  |  |  |  |  |  |  |  |
AMAC III |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | 1,300,000 | 1,900,000 | 3,300,000 |  |  |  |  |  |
(Income) loss from equity affiliates |  |  |  |  |  |  |  |  |  |  | 1,300,000 | 900,000 |  |  |  |  |  |  |
Distribution received |  |  |  |  |  |  |  |  |  |  | 3,800,000 | 100,000 |  |  |  |  |  |  |
Lexford Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distribution received |  |  |  |  |  |  |  |  |  |  | $ 1,100,000 | 3,500,000 |  |  |  |  |  |  |
Lexford Portfolio | Bridge Loans | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Paydowns of principal made by borrower |  |  |  |  |  |  |  |  |  | $ 250,000,000.0 |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00% |  |  |  |  |
Unsecured financing provided by an unsecured lender to certain parent entities of the property owners |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50,000,000.0 |  |  |  |  |
Two portfolios of multifamily properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of loan assumption fee |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,700,000 |  |  |
Equity investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,200,000 |  |  |
Ginkgo Investment Company LLC [Member] | Fannie Mae Mortgage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loan purchased a multifamily apartment complex which assumed |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,300,000 |  |  |  |
Percentage of maximum loss-sharing obligation unpaid principal balance |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  |  |  |
Servicing revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |
Percentage of loan assumption fee |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |
Percentage of ownership after transaction |  |  |  |  |  |  |  |  |  |  | 3.60% |  |  |  |  |  |  |  |
ACM, Certain executives and Consortium of independent outside investors | Mature date of April 2030 | Private Label |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  | 3.10% |  |  |  |  |  |  |  |  |  |  |
ACM, Certain executives and Consortium of independent outside investors | Mature date of April 2030 | Mezzanine Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  | 9.00% |  |  |  |  |  |  |  |  |  |  |
ACM, Certain executives and Consortium of independent outside investors | AMAC III |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount invested | $ 20,300,000 |  |  |  |  |  |  |  |  |  | $ 20,300,000 |  | $ 30,000,000.0 |  |  |  |  | $ 20,300,000 |
Ownership interest (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  | 18.00% |  |  |  |  |  |
ACM, Certain executives and Consortium of independent outside investors | AMAC III | Private Label |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  | 3.735% |  |  |  |  |  |
Amount of loan to related party |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,600,000 |  |  |  |  |  |
ACM, Certain executives and Consortium of independent outside investors | AMAC III | Bridge Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of loan to related party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 34,000,000.0
Unaffiliated borrower | AMAC III | Mezzanine Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of loan to related party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,000,000.0
ACM |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |
ACM | Residential Mortgage Banking Company |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Noncontrolling interest in equity method investment acquired (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |
Indirect ownership percentage |  |  |  | 12.30% |  |  |  |  |  |  |  |  |  |  |  |  | 22.50% |  |
Acquisition purchase price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,600,000 |  |
(Income) loss from equity affiliates |  |  |  |  |  |  |  |  |  |  | $ 34,600,000 |  | 7,200,000 |  |  |  |  |  |
Distribution received |  |  |  |  |  |  |  |  |  |  |  | $ 75,700,000 |  |  |  |  |  |  |
ACM | ACM Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares held by related party | shares | 2,535,870 |  |  |  |  |  |  |  |  |  | 2,535,870 |  |  |  |  |  |  | 2,535,870 |
OP units hold as part of acquisition | shares |  |  |  |  |  |  |  |  |  |  |  | 10,665,530 |  |  |  |  |  |  |
Aggregate percentage of voting power held by related party | 8.00% |  |  |  |  |  |  |  |  |  | 8.00% |  |  |  |  |  |  | 8.00% |
ACM | Preferred equity interest financing agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 | 1,800,000 |  |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Maturity Date January 2019 [Member] | Multifamily Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties owned | property |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Preferred equity investments | Multifamily Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity investment |  |  |  |  |  |  |  | $ 3,400,000 |  |  |  |  |  |  |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Bridge Loan One Multifamily Property [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 61,200,000 |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  |  | 1,300,000 |  |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Bridge Loan One Multifamily Property [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.50% |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.00% |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Bridge Loan One Multifamily Property [Member] | Maturity Date Of August 2022 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount | $ 34,000,000.0 |  |  |  |  |  | $ 35,400,000 |  |  |  | $ 34,000,000.0 |  |  |  |  |  |  | $ 34,000,000.0 |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Bridge Loan One Multifamily Property [Member] | Maturity Date Of August 2022 [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Variable rate, spread (as a percent) |  |  |  |  |  |  | 3.50% |  |  |  |  |  |  |  |  |  |  |  |
Consortium of investors including other unaffiliated investors, certain of officers and chief executive officer | Bridge Loan Two Multifamily Properties [Member] | Maturity Date January 2019 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  | $ 14,800,000 |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |
Consortium of investors including an immediate family member of our officers | Multifamily Portfolio | Fannie Mae Mortgage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of maximum loss-sharing obligation unpaid principal balance |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00% |  |  |  |
Servicing revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 46,900,000 |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17.60% |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 21,700,000 |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.75% |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.25% |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | 1,300,000 | 1,400,000 | 1,400,000 |  |  |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of January 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Due to related party |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,400,000 |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00% |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.25% |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 400,000 |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of June 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Due to related party |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 32,800,000 |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 90.00% |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.00% |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.13% |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  |  | 1,700,000 |  |  |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of July 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Due to related party |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,500,000 |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  | 85.00% |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | 100,000 | 1,300,000 |  |  |  |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Several Multifamily Properties [Member] | Maturity Date Of July 2021 [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00% |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.125% |  |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan One Multifamily Property [Member] | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | 1,400,000 | 2,700,000 |  |  |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity date of October 2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 31,100,000 |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.80% |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity date of October 2021 | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00% |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity Date Of Fourth Quarter 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 28,000,000.0 |  |  |  |
Number of properties owned | property |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 45.00% |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.25% |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | 1,900,000 | 1,900,000 | 2,200,000 |  |  |  |  |  |
Number of mortgage loans secured by property purchased from related party | loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity Date Of Fourth Quarter 2020 [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.24% |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity Date Of Fourth Quarter 2020 [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.54% |  |  |  |
Certain certain officers, chief executive officer, and other unaffiliated investors | Bridge Loan Two Multifamily Properties [Member] | Maturity Date January 2019 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | $ 300,000 | 300,000 | $ 600,000 |  |  |  |  |  |
Chairman and Chief executive officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reimbursement for flights chartered by the company's executives |  |  |  |  |  |  |  |  |  |  |  | $ 500,000 |  |  |  |  |  |  |
Director | Ginkgo Investment Company LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of managing member |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.00% |  |  |  |
Immediate family member of chief executive officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest (as a percent) | 10.00% |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  | 10.00% |
Immediate family member of chief executive officer | Matures in October 2023 [Member] | Preferred equity interest financing agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | $ 500,000 |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Preferred equity investments | Matures in October 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  | 12.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Preferred equity investments | Matures in April 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  | 12.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity participation interest (as a percentage) |  |  |  |  | 21.80% | 18.90% |  |  |  |  |  | 21.80% |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Land |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 17,700,000 |  |  |  |  |
Paydowns of principal made by borrower |  |  |  |  |  |  |  |  | $ 4,700,000 |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.80% |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Matures in October 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Matures in October 2023 [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  | 5.50% |  |  |  |  |  |  | 5.50% |  |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  | 0.75% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Matures in May 2023 [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount invested | $ 3,500,000 |  |  |  |  |  |  |  |  |  | 3,500,000 |  |  |  |  |  |  | $ 3,500,000 |
Base spread (as a percent) |  |  |  |  |  | 5.50% |  |  |  |  |  |  |  |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  | 0.75% |  |  |  |  |  |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Matures in April 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loans | Mature date of April 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | 600,000 |  |  |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loan Several Multifamily Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  | 23.90% |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  | 2.375% |  |  |  |  |  |
Immediate family member of chief executive officer | Bridge Loan Several Multifamily Properties [Member] | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  | 4.25% |  |  |  |  |  |
Lexford Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity affiliates |  |  |  |  |  |  |  |  |  |  |  | (1,100,000) | $ (3,500,000) |  |  |  |  |  |
Maximum exposure under guaranty | 612,900,000 |  |  |  |  |  |  |  |  |  | 612,900,000 |  |  |  |  |  |  | 612,900,000 |
Lexford Portfolio | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  |  | 500,000 | 9,600,000 |  |  |  |  |  |
Lexford Portfolio | Bridge Loans | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of bridge loans originated | loan |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 |  |  |  |  |
Number of multifamily properties renovated | property |  |  |  |  |  |  |  |  |  |  |  |  |  | 72 |  |  |  |  |
Lexford Portfolio | Bridge Loan Two Multifamily Properties [Member] | Maturity Date Of June 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 280.50% |  |  |  |  |
Entity controlled by our chief executive officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reimbursement for flights chartered by the company's executives |  |  |  |  |  |  |  |  |  |  |  |  | 100,000 |  |  |  |  |  |
Certain Officers And Managers [Member] | Mezzanine Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed rate of interest (as a percent) |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |
Certain Officers And Managers [Member] | Bridge Loan Six Multifamily Properties [Member] | Maturity Date September 2019 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 48,000,000.0 |  |  |
Number of properties owned | property |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6 |  |  |
Base spread (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.50% |  |  |
LIBOR floor (as a percentage) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.25% |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | $ 200,000 | $ 200,000 | $ 300,000 |  |  |  |  |  |
Proceeds from repayment of debt |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 28,300,000 |  |  |  |  |
Proceeds from repayment in full |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,800,000 |  |  |  |
Certain Officers And Managers [Member] | Bridge Loan Six Multifamily Properties [Member] | Maturity Date September 2019 [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |
Certain Officers And Managers [Member] | Bridge Loan Six Multifamily Properties [Member] | Maturity Date September 2019 [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest of related party in the entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12.00% |  |  |
Consortium Of Affiliated Investors [Member] | Lexford Portfolio |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee, percentage of gross revenues of underlying properties |  |  |  |  |  |  |  |  |  |  | 4.75% |  |  |  |  |  |  |  |
Real estate investment fund sponsored and managed by Chief executive officer and immediate family member of chief executive officer | Bridge Loans | Maturity date of March 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loan committed |  |  | $ 63,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income recorded |  |  |  |  |  |  |  |  |  |  | $ 2,100,000 |  |  |  |  |  |  |  |
Real estate investment fund sponsored and managed by Chief executive officer and immediate family member of chief executive officer | Bridge Loans | Maturity date of March 2024 | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base spread (as a percent) |  |  | 3.75% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
LIBOR floor (as a percentage) |  |  | 0.25% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount invested | $ 4,200,000 |  |  |  |  |  |  |  |  |  | $ 4,200,000 |  |  |  |  |  |  | $ 4,200,000 |
Ownership interest (as a percent) | 49.30% |  |  |  |  |  |  |  |  |  | 49.30% |  |  |  |  |  |  | 49.30% |
Promissory note with AMC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreements and transactions with related parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Related party financing |  | $ 40,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding principal balance of related party financing |  | $ 40,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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