CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	PREFERRED SHARES [Member]	COMMON SHARES [Member]	ACCUMULATED DISTRIBUTIONS IN EXCESS OF NET INCOME [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME [Member]	NONREDEEMABLE NONCONTROLLING INTERESTS [Member]	Series A Preferred Stock [Member]	Series A Preferred Stock [Member] ACCUMULATED DISTRIBUTIONS IN EXCESS OF NET INCOME [Member]	Series B Preferred Stock [Member]	Series B Preferred Stock [Member] ACCUMULATED DISTRIBUTIONS IN EXCESS OF NET INCOME [Member]	Series C Preferred Stock [Member]	Series C Preferred Stock [Member] PREFERRED SHARES [Member]	Series C Preferred Stock [Member] ACCUMULATED DISTRIBUTIONS IN EXCESS OF NET INCOME [Member]
Balance at Apr. 30, 2015	$ 740,954	$ 138,674	$ 951,868	$ (438,432)		$ 88,844
Balance (in shares) at Apr. 30, 2015			124,455
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Investors Real Estate Trust and noncontrolling interests	76,568			72,006		4,562
Distributions – common shares and units	(71,290)			(64,060)		(7,230)
Distributions - preferred shares	(11,514)						$ (2,372)	$ (2,372)	$ (9,142)	$ (9,142)
Distribution reinvestment and share purchase plan	5,619		$ 5,619
Distribution reinvestment and share purchase plan (in shares)			821
Shares issued and share-based compensation	1,728		$ 1,728
Shares issued and share-based compensation (in shares)			185
Partnership units issued	18,226					18,226
Redemption of units for common shares	0		$ 1,477			(1,477)
Redemption of units for common shares (in shares)			273
Shares repurchased	(35,000)		$ (35,000)
Shares repurchased (in shares)			(4,643)
Distributions to nonredeemable noncontrolling interests – consolidated real estate entities	(7,029)					(7,029)
Adjustments to prior year redemption of units for common shares	0		$ (3,608)			3,608
Balance at Apr. 30, 2016	718,262	138,674	$ 922,084	(442,000)		99,504
Balance (in shares) at Apr. 30, 2016			121,091
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Investors Real Estate Trust and noncontrolling interests	30,947			43,347		(12,400)
Distributions – common shares and units	(63,360)			(55,907)		(7,453)
Distributions - preferred shares	(10,546)						$ (1,403)	$ (1,403)	(9,143)	(9,143)
Shares issued and share-based compensation	358		$ 358
Shares issued and share-based compensation (in shares)			389
Redemption of units for common shares	0		$ 875			(875)
Redemption of units for common shares (in shares)			503
Redemption of units for cash	(966)					(966)
Shares repurchased	(33,253)	(27,317)	$ (4,501)	(1,435)
Shares repurchased (in shares)			(778)
Contributions from nonredeemable noncontrolling interests – consolidated real estate entities	7,188					7,188
Conversion to equity of notes receivable from nonredeemable noncontrolling interests – consolidated real estate entities	(7,366)					(7,366)
Acquisition of nonredeemable noncontrolling interests – consolidated real estate entities	(4,938)		$ (2,677)			(2,261)
Other	(232)		$ (18)			(214)
Other (in shares)			(6)
Balance at Apr. 30, 2017	636,094	111,357	$ 916,121	(466,541)	$ 0	75,157
Balance (in shares) at Apr. 30, 2017			121,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Investors Real Estate Trust and noncontrolling interests	128,370			116,788		11,582
Other comprehensive income - derivative instrument	1,779				1,779
Distributions – common shares and units	(37,785)			(33,689)		(4,096)
Distributions - preferred shares	(8,569)								$ (4,571)	$ (4,571)	$ (3,999)		$ (3,999)
Shares issued and share-based compensation	1,663		$ 1,663
Shares issued and share-based compensation (in shares)			96
Issuance of Series C preferred shares											$ 99,456	$ 99,456
Redemption of units for common shares	0		$ 34			(34)
Redemption of units for common shares (in shares)			29
Redemption of units for cash	(8,775)					(8,775)
Shares repurchased	(124,949)	(111,357)	$ (9,935)	(3,657)
Shares repurchased (in shares)			(1,780)
Contributions from nonredeemable noncontrolling interests – consolidated real estate entities	619					619
Conversion to equity of notes receivable from nonredeemable noncontrolling interests – consolidated real estate entities	(246)					(246)
Other	(157)		$ (40)			(117)
Other (in shares)			(18)
Balance at Apr. 30, 2018	$ 687,499	$ 99,456	$ 907,843	$ (395,669)	$ 1,779	$ 74,090
Balance (in shares) at Apr. 30, 2018			119,526