Agreements and Transactions with Related Parties, Other (Details) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended | | |
Apr. 30, 2018USD ($) | Dec. 31, 2017USD ($)property | Aug. 31, 2017USD ($) | Jul. 31, 2017USD ($) | May 31, 2017USD ($) | Mar. 31, 2017USD ($)item | Jan. 31, 2017USD ($) | Mar. 31, 2018USD ($)shares | Dec. 31, 2017USD ($)propertyitem | Mar. 31, 2017USD ($)item | Dec. 31, 2017USD ($)propertyshares | Dec. 31, 2016USD ($)propertyshares | Dec. 31, 2015USD ($)loan | Dec. 31, 2014USD ($)loanitem | Jan. 31, 2018USD ($) | Mar. 31, 2016USD ($) |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Due from related party | | $ 688 | | | | | | $ 3,719 | $ 688 | | $ 688 | | | | | |
Due to related party | | | | | | | | 1,558 | | | | | | | | |
Related party financing | | 50,000 | | | | | | | 50,000 | | 50,000 | | | | | |
Outstanding principal balance of related party financing | | 50,000 | | | | | | | 50,000 | | 50,000 | | | | | |
Income from equity affiliates | | | | | | | | 746 | | $ 763 | | | | | | |
Investments in equity affiliates | | 23,653 | | | | | | 23,625 | 23,653 | | 23,653 | | | | | |
Residential Mortgage Banking Company | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Maximum percentage of guaranty provided by the Company in relation to the settlement | | | | | | | | | | | | | 50.00% | | | |
Maximum exposure under this guaranty | | | | | | | | | | | | | $ 3,100 | | | |
Preferred equity investments | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | 5,000 | | | | | $ 15,000 | | 5,000 | | 5,000 | | | | | |
Commitment to fund additional investment | | | | | | | $ 5,000 | | | | | | | | | |
Interest income recorded | | | | | | | | | | 200 | | | | | | |
Fixed rate of interest (as a percent) | | | | | | | 11.00% | | | | | | | | | |
Amount of ownership interest of related party in the entity | | | | | | | $ 5,000 | | | | | | | | | |
Mezzanine loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Interest income recorded | | | | | | | | 100 | | 100 | | | | | | |
Fixed rate of interest (as a percent) | | | | | | | | | | | | | 12.50% | | | |
Amount of loan to related party | | | | | | | | | | | | | $ 3,000 | | | |
ACM / Our "Former Manager" | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Due from related party | | 700 | | | | | | 3,700 | 700 | | $ 700 | | | | | |
Due to related party | | | | | | | | 1,600 | | | | | | | | |
Related party financing | | | | | | | | | | | | | | | $ 50,000 | |
Interest expense on related party loan | | | | | | | | 300 | | 1,000 | | | | | | |
Outstanding principal balance of related party financing | | | | | | | | | | | | | | | $ 50,000 | |
ACM / Our "Former Manager" | 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 | | | | | | | | | | | | | 22.5% | | | |
Acquisition purchase price | | | | | | | | | | | | | $ 9,600 | | | |
Income from equity affiliates | | | | | | | | $ 100 | | 100 | | | | | | |
Maximum percentage of guaranty provided by the Company in relation to the settlement | | | | | | | | | | | | | 50.00% | | | |
ACM / Our "Former Manager" | ACM Acquisition | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Number of preferred stock shares paired with each OP units | shares | | | | | | | | | | | | 1 | | | | |
Number of shares held by related party | shares | | | | | | | | 5,349,053 | | | | | | | | |
OP units hold as part of acquisition | shares | | | | | | | | 15,450,421 | | | 5,780,348 | 21,230,769 | | | | |
Percentage of voting power held by related party | | | | | | | | | | | | 24.80% | | | | |
ACM / Our "Former Manager" | Non-qualified Residential Mortgages | Residential Mortgage Banking Company | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Additional investment made by the company along with a consortium of independent outside investors | | | | | | | | | | | | | $ 16,100 | | | |
Distributions received | | | | | | | | $ 200 | | | | | 16,400 | | | |
ACM / Our "Former Manager" | Mortgage loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | | $ 47,000 | | | |
ACM / Our "Former Manager" | Preferred equity interest financing agreement | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Related party financing | | 50,000 | | | | | | | 50,000 | | $ 50,000 | | | | | |
Interest expense on related party loan | | | | | | | | 300 | | 1,000 | | | | | | |
Outstanding principal balance of related party financing | | 50,000 | | | | | | | 50,000 | | 50,000 | | | | | |
ACM / Our "Former Manager" | Maturity date of April 2016 | Mortgage loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Base spread (as a percent) | | | | | | | | | | | | | | 4.80% | | |
Interest income recorded | | | | | | | | 200 | | 200 | | | | | | |
Number of mortgage loans secured by property purchased from related party | loan | | | | | | | | | | | | | | 2 | | |
ACM / Our "Former Manager" | Maturity date of April 2016 | Mortgage loans | First mortgage | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | | | $ 14,600 | | |
ACM / Our "Former Manager" | Maturity date of April 2016 | Mortgage loans | Second mortgage | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Proceeds from repayment in full | | | | | | | | | | | | $ 5,100 | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | | | $ 5,100 | | |
ACM / Our "Former Manager" | Maturity date April 2018, extended from April 2016 | Mortgage loans | First mortgage | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | | | | | $ 14,600 |
Consortium of investors including an immediate family member of our officers | Fannie Mae loan on a multifamily property | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of maximum loss-sharing obligation unpaid principal balance | | | | | 5.00% | | | | | | | | | | | |
Principal amount | | | | | $ 46,900 | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | | 21.40% | | | | | | | | | | | |
Consortium of investors including an immediate family member of our officers | Fannie Mae loan on a multifamily property | Maximum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Servicing revenue | | | | | | | | 100 | | | | | | | | |
Consortium of Investors, including our Chief Executive Officer and our Former Manager | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Amount invested | | | | | | $ 2,000 | | | | $ 2,000 | | | | | | |
Ownership interest (as a percent) | | | | | | 26.10% | | | | 26.10% | | | | | | |
Number of portfolios of multifamily properties | item | | | | | | 2 | | | | 2 | | | | | | |
Certain officers, including our Chief Executive Officer and our Former Manager | Maturity Date of January 2021 | Bridge loan, several multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Due to related party | $ 9,400 | | | | | | | | | | | | | | | |
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% | | | | | | | | | | | | | | | |
Certain officers, including our Chief Executive Officer and our Former Manager | Maturity date of September 2019 | Bridge loan, six multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | | | | | | | | | | | $ 48,000 | | | | |
Number of properties owned | property | | | | | | | | | | | | 6 | | | | |
Base spread (as a percent) | | | | | | | | | | | | 4.50% | | | | |
LIBOR floor (as a percentage) | | | | | | | | | | | | 0.25% | | | | |
Interest income recorded | | | | | | | | 600 | | $ 700 | | | | | | |
Proceeds from repayment in full | | | $ 6,800 | | | | | | | | | | | | | |
Certain officers, including our Chief Executive Officer and our Former Manager | Maturity date of September 2019 | Bridge loan, six multifamily properties | Minimum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | 10.50% | | | | |
Certain officers, including our Chief Executive Officer and our Former Manager | Maturity date of September 2019 | Bridge loan, six multifamily properties | Maximum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | 12.00% | | | | |
Certain officers, including our Chief Executive Officer and our Former Manager | Maturity Date of October 2018 | Bridge loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Base spread (as a percent) | | | | | | | | | | | | | 5.00% | | | |
LIBOR floor (as a percentage) | | | | | | | | | | | | | 0.25% | | | |
Interest income recorded | | | | | | | | 300 | | 300 | | | | | | |
Number of mortgage loans secured by property purchased from related party | loan | | | | | | | | | | | | | 2 | | | |
Loan due from related party | | | | | | | | | | | | | $ 16,700 | | | |
Certain Officers | Maturity date of June 2020 | Bridge loan, several multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Due to related party | | $ 32,800 | | | | | | | $ 32,800 | | $ 32,800 | | | | | |
Percentage of ownership after transaction | | 90.00% | | | | | | | | | | | | | | |
Base spread (as a percent) | | 5.00% | | | | | | | 5.00% | | 5.00% | | | | | |
LIBOR floor (as a percentage) | | 1.13% | | | | | | | | | | | | | | |
Interest income recorded | | | | | | | | 500 | | | | | | | | |
Certain Officers | Maturity date of fourth quarter 2020 | Bridge loan, two multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | $ 28,000 | | | | | | | $ 28,000 | | $ 28,000 | | | | | |
Number of properties owned | property | | 2 | | | | | | | 2 | | 2 | | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | 45.00% | | | | | | | |
Base spread (as a percent) | | 5.25% | | | | | | | 5.25% | | 5.25% | | | | | |
Interest income recorded | | | | | | | | 500 | | | | | | | | |
Number of bridge loans originated | item | | | | | | | | | 2 | | | | | | | |
Certain Officers | Maturity date of fourth quarter 2020 | Bridge loan, two multifamily properties | Minimum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
LIBOR floor (as a percentage) | | | | | | | | | 1.24% | | | | | | | |
Certain Officers | Maturity date of fourth quarter 2020 | Bridge loan, two multifamily properties | Maximum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
LIBOR floor (as a percentage) | | | | | | | | | 1.54% | | | | | | | |
Certain Officers | Maturity date of July 2020 | Bridge loan, one multifamily property | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | | | $ 36,000 | | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | 95.00% | | | | | | | | | | | | |
Base spread (as a percent) | | | | 4.50% | | | | | | | | | | | | |
LIBOR floor (as a percentage) | | | | 1.00% | | | | | | | | | | | | |
Interest income recorded | | | | | | | | 600 | | | | | | | | |
Certain Officers | Maturity date of January 2019 | Bridge loan, two multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | | | | | | | | | | | $ 12,700 | | | | |
Number of properties owned | property | | | | | | | | | | | | 2 | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | 50.00% | | | | |
Base spread (as a percent) | | | | | | | | | | | | 4.50% | | | | |
LIBOR floor (as a percentage) | | | | | | | | | | | | 0.25% | | | | |
Interest income recorded | | | | | | | | 300 | | 300 | | | | | | |
Certain Officers | Maturity date of January 2019 | Bridge loan, one multifamily property | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | | | | | | | | | | | $ 19,000 | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | 7.50% | | | | |
Base spread (as a percent) | | | | | | | | | | | | 4.50% | | | | |
LIBOR floor (as a percentage) | | | | | | | | | | | | 0.25% | | | | |
Interest income recorded | | | | | | | | $ 300 | | 300 | | | | | | |
Certain Officers | Maturity date May 2018, extended from November 2017 | Preferred equity investments | Multifamily | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Equity investment | | | | | | | | | | | | $ 5,200 | | | | |
Fixed rate of interest (as a percent) | | | | | | | | | | | | 10.00% | | | | |
Certain Officers | Maturity date of November 2018 | Bridge loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | | 7.50% | | | |
Base spread (as a percent) | | | | | | | | | | | | | 4.50% | | | |
LIBOR floor (as a percentage) | | | | | | | | | | | | | 0.25% | | | |
Interest income recorded | | | | | | | | | | 100 | | | | | | |
Amount of loan to related party | | | | | | | | | | | | | $ 7,100 | | | |
Chief executive officer | Minimum | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Ownership interest allowed under company charter (as a percent) | | | | | | | | 5.00% | | | | | | | | |
Chief executive officer | Bridge loan, two multifamily properties | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Number of properties owned | item | | | | | | | | | | | | | | 2 | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | | | 95.00% | | |
Base spread (as a percent) | | | | | | | | | | | | | | 5.50% | | |
Interest income recorded | | | | | | | | | | 100 | | | | | | |
Amount of loan to related party | | | | | | | | | | | | | | $ 1,700 | | |
Investments in equity affiliates | | | | | | | | | | | | | | $ 100 | | |
Ownership interest (as a percent) | | | | | | | | | | | | | | 5.00% | | |
Chief executive officer | Maturity date of August 2017 | Bridge loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of ownership interest of related party in the entity | | | | | | | | | | | | | | 24.00% | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | | | $ 30,400 | | |
Chief executive officer | Maturity date of August 2020 | Bridge loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Base spread (as a percent) | | | 4.00% | | | | | | | | | | | | | |
LIBOR floor (as a percentage) | | | 1.23% | | | | | | | | | | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | $ 43,200 | | | | | | | | | | | | | |
Mr. Ivan Kaufman and his affiliates | Maturity date of August 2017 | Mezzanine loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Interest income recorded | | | | | | | | | | 800 | | | | | | |
Fixed rate of interest (as a percent) | | | | | | | | | | | | 12.00% | | | | |
Amount of mortgage loan secured by property, purchased by related party | | | | | | | | | | | | $ 4,600 | | | | |
Kaufman Entities | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of our Former Manager's outstanding membership interest of related party in another related party | | | | | | | | 75.00% | | | | | | | | |
Affiliate of Mr. Ivan Kaufman | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Contract period with the new entity | | | | | | | | 7 years 6 months | | | | | | | | |
Fees as a percentage of gross revenues of the underlying properties | | | | | | | | 4.75% | | | | | | | | |
Lexford Portfolio | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Aggregate outstanding balance of related party debt | | | | | | | | $ 310,300 | | | | | | | | |
Lexford Portfolio | Preferred equity investments | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Income from equity affiliates | | | | | | | | $ 600 | | 700 | | | | | | |
Ginkgo | Fannie Mae | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Loan purchased a multifamily apartment complex which assumed | | | | | | | $ 8,300 | | | | | | | | | |
Percentage of maximum loss-sharing obligation unpaid principal balance | | | | | | | 20.00% | | | | | | | | | |
Percentage of loan assumption fee | | | | | | | 1.00% | | | | | | | | | |
Percentage of ownership after transaction | | | | | | | | 3.60% | | | | | | | | |
Ginkgo | Maximum | Fannie Mae | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Servicing revenue | | | | | | | | $ 100 | | 100 | | | | | | |
Lexford Portfolio | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Income from equity affiliates | | | | | | | | 600 | | 700 | | | | | | |
Two portfolios of multifamily properties | Consortium of Investors, including our Chief Executive Officer and our Former Manager | Maturity date of November 2018 | Bridge loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Principal amount | | | | | | $ 14,800 | | | | $ 14,800 | | | | | | |
Base spread (as a percent) | | | | | | 5.25% | | | | 5.25% | | | | | | |
LIBOR floor (as a percentage) | | | | | | 0.50% | | | | | | | | | | |
Interest income recorded | | | | | | | | $ 200 | | $ 200 | | | | | | |
Number of bridge loans originated | item | | | | | | 2 | | | | | | | | | | |
Two portfolios of multifamily properties | Certain officers, including our Chief Executive Officer and our Former Manager | Maturity date of November 2018 | Mortgage loans | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Proceeds from repayment of debt | | | | | | | | | $ 6,500 | | | | | | | |
Ginkgo | Director | | | | | | | | | | | | | | | | |
Agreements and transactions with related parties | | | | | | | | | | | | | | | | |
Percentage of managing member | | | | | | | 33.00% | | | | | | | | | |