BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Real Estate Properties (Details)	12 Months Ended
	Apr. 30, 2017 USD ($) property item $ / shares shares	Dec. 31, 2016	Apr. 30, 2016 USD ($) property $ / shares	Dec. 31, 2015	Apr. 30, 2015 USD ($) property $ / shares
BASIS OF PRESENTATION [Abstract]
Interest in operating partnership (in hundredths)	88.60%		88.10%
Percentage of general interest partnership (in hundredths)	100.00%		100.00%
Redemption basis	1:1
Redemptions by limited partner, maximum | item	2
Number of units to redeem, minimum (in units) | shares	1,000
Period to hold the beneficial interest, minimum	1 year
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 57,028,000		$ 5,983,000		$ 6,105,000
IDENTIFIED INTANGIBLE ASSETS AND LIABILITIES AND GOODWILL [Abstract]
New intangible assets	0		2,200,000
Addition to intangible liabilities	0		$ 101,000
Weighted average lives of intangible assets acquired			8 months 12 days
Goodwill book value	1,572,000		$ 1,680,000
Recognized impairment goodwill	0		0
PROPERTY AND EQUIPMENT [Abstract]
Property and equipment cost	2,100,000		2,100,000
Accumulated depreciation	1,199,000		1,058,000
REAL ESTATE DEPOSITS [Abstract]
Deposits held in escrow	$ 23,700,000		$ 0
INCOME TAXES [Abstract]
Minimum dividend distribution percentage (in hundredths)	90.00%
Dividend distribution percentage (in hundredths)	90.00%		90.00%		90.00%
Distribution of federal income tax (in hundredths)		12.43%		36.28%
Distribution of capital gain (in hundredths)		87.57%		11.99%
Distribution made as return of capital (in hundredths)				51.73%
REVISION [Abstract]
Interest income	$ 369,000		$ 81,000		$ 62,000
Income before gain on sale of real estate and other investments, gain on bargain purchase and income from discontinued operations	(56,851,000)		4,041,000		11,237,000
Income from continuing operations	(38,150,000)		17,105,000		17,330,000
Income from discontinued operations	$ 68,675,000		$ 59,497,000		$ 11,354,000
Earnings per common share from continuing operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares	$ (0.24)		$ 0.06		$ 0.02
Earnings per common share from discontinued operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares	$ 0.50		$ 0.43		$ 0.09
REAL ESTATE INVESTMENTS [Abstract]
Number of year after date of acquisition related to adjustment of real estate preliminary allocations of purchase price	1 year
Scenario, Previously Reported [Member]
REVISION [Abstract]
Interest income			$ 2,256,000
Income before gain on sale of real estate and other investments, gain on bargain purchase and income from discontinued operations			6,216,000
Income from continuing operations			19,280,000
Income from discontinued operations			$ 57,322,000
Earnings per common share from continuing operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares			$ 0.08
Earnings per common share from discontinued operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares			$ 0.41
Restatement Adjustment [Member]
REVISION [Abstract]
Interest income			$ (2,175,000)
Income before gain on sale of real estate and other investments, gain on bargain purchase and income from discontinued operations			(2,175,000)
Income from continuing operations			(2,175,000)
Income from discontinued operations			$ 2,175,000
Earnings per common share from continuing operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares			$ (0.02)
Earnings per common share from discontinued operations - Investors Real Estate Trust - basic and diluted (in dollars per share) | $ / shares			$ 0.02
Buildings and Improvements [Member] | Minimum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	20 years
Buildings and Improvements [Member] | Maximum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	40 years
Furniture, Fixtures and Equipment [Member] | Minimum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	5 years
Furniture, Fixtures and Equipment [Member] | Maximum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	12 years
Renovations and Improvements [Member] | Minimum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	5 years
Renovations and Improvements [Member] | Maximum [Member]
REAL ESTATE INVESTMENTS [Abstract]
Estimated useful life of assets (in years)	10 years
Minot, ND - property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 2,900,000
Multi-family Residential Properties [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property	16
Multi-family Residential Properties [Member] | Williston, ND - property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property	3
Multi-family Residential Properties [Member] | Williston, ND - property 1 [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 40,900,000
Interest in joint venture (in hundredths)	70.00%
Multi-family Residential Properties [Member] | Williston, ND - property 2 [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 5,800,000
Multi-family Residential Properties [Member] | Williston, ND - property 3 [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 4,700,000
Interest in joint venture (in hundredths)	60.00%
Multi-Family Residential [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property			8
Multi-Family Residential [Member] | St Cloud Minnesota Member
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			$ 1,900,000
Number of impaired properties | property			8
Unimproved Land [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property	2		2		2
Unimproved Land [Member] | Williston, ND - property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments	$ 2,800,000
Interest in joint venture (in hundredths)	70.00%
Number of impaired properties | property	1
Unimproved Land [Member] | Minot, ND - property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property	1
Unimproved Land [Member] | River Falls Wisconsin Member
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			$ 162,000
Unimproved Land [Member] | Eagan, Minnesota, Unimproved Land [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					$ 98,000
Unimproved Land [Member] | Weston, Wisconsin, Unimproved Land [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					$ 442,000
Commercial Properties [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property					4
IDENTIFIED INTANGIBLE ASSETS AND LIABILITIES AND GOODWILL [Abstract]
Number of real estate properties disposed | property	4		8
Goodwill derecognized	$ 103,000		$ 196,000
Commercial Healthcare [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property			1
Office [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property			1
Retail [Member] | Kalispell, Montana, Retail Property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					$ 2,100,000
Office Property [Member] | Eden Prairie Minnesota Member
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			$ 440,000
Office Property [Member] | Golden Valley, Minnesota [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					183,000
Office Property [Member] | Minneapolis, Minnesota, Office Property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					1,800,000
Office Property [Member] | Boise, Idaho, Office Property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments					1,400,000
Assets Held for Sale [Member] | Multi-family Residential Properties [Member]
Held for Sale [Abstract]
Number of real estate properties classified as held for sale | property	13		1
Assets Held for Sale [Member] | Multi-family Residential Properties [Member] | Minot, ND - property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Number of impaired properties | property	13
Assets Held for Sale [Member] | Unimproved Land [Member]
Held for Sale [Abstract]
Number of real estate properties classified as held for sale | property			3
Assets Held for Sale [Member] | Commercial Healthcare [Member]
Held for Sale [Abstract]
Number of real estate properties classified as held for sale | property	2		35
Assets Held for Sale [Member] | Industrial [Member]
Held for Sale [Abstract]
Number of real estate properties classified as held for sale | property			1
Assets Held for Sale [Member] | Retail [Member]
Held for Sale [Abstract]
Number of real estate properties classified as held for sale | property	2
Assets Held for Sale [Member] | Medical Property [Member] | Sartell, Minnesota, Healthcare Property [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			$ 1,900,000
Discontinued Operations [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			440,000		1,400,000
REVISION [Abstract]
Interest income	$ 2,176,000		2,176,000		2,176,000
Income from discontinued operations	$ 68,675,000		59,497,000		$ 11,354,000
Discontinued Operations [Member] | Unimproved Land [Member] | Grand Chute, Wisconsin, Unimproved Land [Member]
IMPAIRMENT OF LONG-LIVED ASSETS [Abstract]
Impairment of real estate investments			$ 1,600,000