BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)			1 Months Ended		2 Months Ended	3 Months Ended										8 Months Ended	12 Months Ended
	Dec. 14, 2018	Apr. 30, 2017	Dec. 31, 2019 USD ($) shares	Aug. 31, 2017 USD ($) property	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Oct. 31, 2018 USD ($) $ / shares	Jul. 31, 2018 USD ($) $ / shares	Apr. 30, 2018 USD ($) $ / shares shares	Jan. 31, 2018 USD ($) $ / shares	Oct. 31, 2017 USD ($) $ / shares	Jul. 31, 2017 USD ($) $ / shares	Dec. 31, 2018 USD ($) property shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2019 USD ($) property shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) apartment_community shares	Dec. 31, 2018 USD ($) shares	Apr. 30, 2018 USD ($) property shares	Dec. 31, 2017	Apr. 30, 2017 USD ($) property	Dec. 27, 2018 shares	Dec. 26, 2018 shares
BASIS OF PRESENTATION [Abstract]
Interest in operating partnership			92.00%		92.00%	92.00%						89.40%				89.70%	92.00%	92.00%	92.00%	92.00%	92.00%	92.00%	89.70%	89.40%
Percentage of general interest partnership			100.00%		100.00%	100.00%						100.00%					100.00%	100.00%	100.00%	100.00%	100.00%	100.00%		100.00%
Stock split conversion ratio	0.10
Common Shares of Beneficial Interest, shares issued (in shares) | shares			12,098,379		12,098,379	12,098,379						11,952,598				11,942,372	12,098,379	12,098,379	12,098,379	12,098,379	12,098,379	12,098,379	11,942,372	11,952,598			11,900,000	119,400,000
Reverse stock split, units (in shares) | shares																											1,400,000	13,700,000
REAL ESTATE INVESTMENTS [Abstract]
Real estate investments			$ 1,311,472,000		$ 1,311,472,000	$ 1,311,472,000						$ 1,380,245,000				$ 1,289,476,000	$ 1,311,472,000	$ 1,311,472,000	$ 1,311,472,000	$ 1,311,472,000	$ 1,311,472,000	$ 1,311,472,000	$ 1,289,476,000	$ 1,380,245,000
Construction period interest capitalized																0			0					4,000		$ 431,000
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																1,221,000			0					18,065,000		57,028,000
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Net income					$ (3,892,000)	46,953,000	$ 29,891,000	$ 1,407,000	$ (6,403,000)	$ (6,264,000)	$ 1,211,000	$ (22,579,000)	$ 134,331,000	$ 6,360,000	$ (13,550,000)	(8,945,000)			71,848,000					$ 104,562,000		$ 31,366,000
Net income (loss) per common share - basic & diluted (in dollars per share) | $ / shares					$ (0.33)					$ (0.52)	$ 0.10	$ (1.89)	$ 11.22	$ 0.53	$ (1.12)
INCOME TAXES [Abstract]
Minimum dividend distribution percentage																				90.00%
Dividend distribution percentage																				90.00%				90.00%		90.00%
Ordinary income																				23.43%			0.00%		14.59%
Capital gain																				38.53%			100.00%		48.87%
Return of capital																				38.04%			0.00%		36.54%
PROPERTY AND EQUIPMENT [Abstract]
Property and equipment cost			2,900,000		$ 2,900,000	2,900,000						$ 2,100,000				2,200,000	2,900,000	2,900,000	2,900,000	$ 2,900,000	2,900,000	2,900,000	$ 2,200,000	$ 2,100,000
Accumulated depreciation			1,700,000		1,700,000	1,700,000						1,300,000				1,400,000	1,700,000	$ 1,700,000	1,700,000	1,700,000	1,700,000	$ 1,700,000	1,400,000	1,300,000
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Number of real estate properties sold																		28				12
Mortgage loans receivable			10,000,000.0	$ 11,000,000.0	10,000,000.0	10,000,000.0						$ 11,000,000.0				10,400,000	10,000,000.0	$ 10,000,000.0	10,000,000.0	10,000,000.0	$ 10,000,000.0	$ 10,000,000.0	$ 10,400,000	11,000,000.0
GAIN ON BARGAIN PURCHASE [Abstract]
Gain (loss) on litigation settlement																$ 0			6,586,000					$ 0		$ 0
Cash received in litigation																			5,200,000
Liabilities waived in litigation																			1,400,000
Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Depreciation																			29,300,000
Net income																			(29,300,000)
Net income (loss) per common share - basic & diluted (in dollars per share) | $ / shares																					$ (0.22)
Assets Held for Sale
HELD FOR SALE [Abstract]
Number of real estate properties classified as held for sale | property																0		0						0
Discontinued Operations, Disposed of by Sale
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Interest and other income																$ 0			0					$ 661,000		$ 2,179,000
Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																								1		16
Multi-family Residential Properties | Assets Held for Sale
HELD FOR SALE [Abstract]
Number of real estate properties classified as held for sale | property																										13
Commercial Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																								3
Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																								4		2
Multi-Family Residential
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Interest rate on mortgages payable											6.00%
Amount funded			6,200,000		6,200,000	6,200,000									$ 341,000		6,200,000	$ 6,200,000	6,200,000	6,200,000	$ 6,200,000	6,200,000
Accrued interest			$ 16,600,000		16,600,000	16,600,000											16,600,000	16,600,000	16,600,000	16,600,000	16,600,000	16,600,000
Multi-Family Residential | Construction Loans
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Interest rate on mortgages payable			4.50%
Multi-Family Residential | Mezzanine Loan
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Interest rate on mortgages payable			11.50%
Multi-Family Residential | Discontinued Operations, Disposed of by Sale
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Number of real estate properties sold | property				13
Interest rate on mortgages payable				5.50%
Interest and other income																448,000			570,000					$ 372,000
Impaired Property Bismark, North Dakota
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																$ 1,200,000
Grand Forks, North Dakota | Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								12,200,000
Grand Forks, North Dakota | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								1,500,000
Bloomington, Minnesota | Industrial
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								1,400,000
Woodbury 1865 Woodland - Woodbury, MN | Industrial
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								922,000
Impaired Property Minot N D
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																										$ 2,900,000
Impaired Property Minot N D | Multi-family Residential Properties | Assets Held for Sale
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																										13
Impaired Property Minot N D | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																										1
Impaired Property Minot N D | Retail Site
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								630,000
Impaired Property Williston Nd | Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																										3
Impaired Property Williston Nd | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								428,000		$ 2,800,000
Number of impaired properties | property																										1
Interest in joint venture		70.00%																								70.00%
Bismark, North Dakota - First Property | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								256,000
Bismark, North Dakota - Second Property | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																								$ 709,000
Bismark, North Dakota | Land
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property																								2
Impaired Property One Williston Nd | Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																										$ 40,900,000
Interest in joint venture		70.00%																								70.00%
Impaired Property Two Williston Nd | Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																										$ 5,800,000
Impaired Property Three Williston Nd | Multi-family Residential Properties
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments																										$ 4,700,000
Interest in joint venture		60.00%																								60.00%
New Hope, Minnesota | Multi-Family Residential
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Loan commitment															$ 16,200,000
Minneapolis, Minnesota | Multi-Family Residential | Construction Loans
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Loan commitment			$ 29,900,000		29,900,000	29,900,000											29,900,000	29,900,000	29,900,000	29,900,000	29,900,000	29,900,000
Minneapolis, Minnesota | Multi-Family Residential | Mezzanine Loan
MORTGAGE LOANS RECEIVABLE AND NOTES RECEIVABLE [Abstract]
Loan commitment			$ 15,300,000		$ 15,300,000	$ 15,300,000											$ 15,300,000	$ 15,300,000	$ 15,300,000	$ 15,300,000	$ 15,300,000	$ 15,300,000
Minimum | Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Useful life		20 years														10 years
Maximum | Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Useful life		40 years														37 years
Building and Building Improvements | Minimum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	10 years
Building and Building Improvements | Maximum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	37 years
Furniture and Fixtures | Minimum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	5 years
Furniture and Fixtures | Maximum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	10 years
Renovations And Improvements | Minimum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	5 years
Renovations And Improvements | Maximum
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets																	20 years
Property With Previous Nine Year Life | Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Useful life		9 years
Property With Previous Nine Year Life | Minimum | Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Useful life																5 years
Property With Previous Nine Year Life | Maximum | Service Life
CHANGE IN DEPRECIABLE LIVES OF REAL ESTATE ASSETS [Abstract]
Useful life																10 years