ACQUISITIONS, DISPOSITIONS AND IMPAIRMENT CHARGES - Property Acquisitions (Details)	4 Months Ended	12 Months Ended
	May 15, 2020 USD ($) property_unit	Dec. 31, 2019 USD ($) property_unit property_Unit	Dec. 31, 2018 USD ($) property_unit
Acquisitions
No. of Units | property_Unit		1,880
Purchase of properties | Primary beneficiary | Multi-family residential | Wilmington, North Carolina | Subsequent Event
Acquisitions
No. of Units | property_unit	264
Purchase Price	$ 38,000,000
Initial BRT Equity	17,100,000
Purchase of properties | Primary beneficiary | Multi-family residential | Mortgages | Wilmington, North Carolina | Subsequent Event
Acquisitions
Acquisition Mortgage Debt	23,200,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures
Acquisitions
No. of Units | property_unit		840	1,863
Purchase Price		$ 109,465,000	$ 237,623,000
Initial BRT Equity		27,176,000	54,669,000
Property acquisition costs		1,245,000	$ 3,122,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | San Marcos, TX
Acquisitions
Purchase Price		$ 1,608,000
Ownership Percentage		20.00%
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Pensacola, FL
Acquisitions
Purchase Price		$ 250,000
Ownership Percentage		2.50%
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Fredricksburg, VA - supplemental
Acquisitions
Purchase Price		$ 4,909,000
Ownership Percentage		20.00%
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Houston, TX (Kendall)
Acquisitions
Purchase Price		$ 3,444,000
Ownership Percentage		20.00%
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Kannapolis, NC
Acquisitions
No. of Units | property_unit		312
Purchase Price		$ 48,065,000
Initial BRT Equity		$ 11,231,000
Ownership Percentage		65.00%
Property acquisition costs		$ 559,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Trussville, AL
Acquisitions
No. of Units | property_unit		328
Purchase Price		$ 43,000,000
Initial BRT Equity		$ 11,625,000
Ownership Percentage		80.00%
Property acquisition costs		$ 546,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Auburn, AL
Acquisitions
No. of Units | property_unit		200
Purchase Price		$ 18,400,000
Initial BRT Equity		$ 4,320,000
Ownership Percentage		80.00%
Property acquisition costs		$ 140,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Ocoee, FL
Acquisitions
No. of Units | property_unit			522
Purchase Price			$ 71,347,000
Initial BRT Equity			$ 12,370,000
Ownership Percentage			50.00%
Property acquisition costs			$ 1,047,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Lawrenceville, GA
Acquisitions
No. of Units | property_unit			586
Purchase Price			$ 77,229,000
Initial BRT Equity			$ 15,179,000
Ownership Percentage			50.00%
Property acquisition costs			$ 767,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Daytona Beach, FL
Acquisitions
No. of Units | property_unit			208
Purchase Price			$ 20,500,000
Initial BRT Equity			$ 6,900,000
Ownership Percentage			80.00%
Property acquisition costs			$ 386,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Grand Prairie, TX
Acquisitions
No. of Units | property_unit			281
Purchase Price			$ 30,800,000
Initial BRT Equity			$ 7,300,000
Ownership Percentage			50.00%
Property acquisition costs			$ 413,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Greenville, SC
Acquisitions
No. of Units | property_unit			266
Purchase Price			$ 37,747,000
Initial BRT Equity			$ 12,920,000
Ownership Percentage			90.00%
Property acquisition costs			$ 509,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Wilmington, North Carolina | Subsequent Event
Acquisitions
Initial BRT Equity	$ 3,400,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages
Acquisitions
Acquisition Mortgage Debt		80,097,000	166,535,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Kannapolis, NC
Acquisitions
Acquisition Mortgage Debt		33,347,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Trussville, AL
Acquisitions
Acquisition Mortgage Debt		32,250,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Auburn, AL
Acquisitions
Acquisition Mortgage Debt		$ 14,500,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Ocoee, FL
Acquisitions
Acquisition Mortgage Debt			53,060,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Lawrenceville, GA
Acquisitions
Acquisition Mortgage Debt			54,447,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Daytona Beach, FL
Acquisitions
Acquisition Mortgage Debt			13,608,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Grand Prairie, TX
Acquisitions
Acquisition Mortgage Debt			18,995,000
Purchase of properties | Primary beneficiary | Multi-family residential | Joint ventures | Mortgages | Greenville, SC
Acquisitions
Acquisition Mortgage Debt			$ 26,425,000