QUARTERLY RESULTS OF CONSOLIDATED OPERATIONS (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Selected Quarterly Financial Information [Abstract]
REVENUE	$ 44,185	$ 42,716	$ 41,866	$ 40,978	$ 42,811	$ 39,797	$ 39,195	$ 38,301	$ 169,745	$ 160,104	$ 145,500
Net income (loss) attributable to Investors Real Estate Trust	(20,874)	136,105	12,821	(11,264)	30,280	23,110	11,600	(21,643)	116,788	43,347	72,006
Net income (loss) available to common shareholders	$ (22,579)	$ 134,331	$ 6,360	$ (13,550)	$ 27,994	$ 19,172	$ 8,722	$ (24,522)	$ 104,562	$ 31,366	$ 60,492
Net income (loss) per common share - basic & diluted (in dollars per share)	$ (0.19)	$ 1.12	$ 0.05	$ (0.11)	$ 0.23	$ 0.16	$ 0.07	$ (0.20)	$ 0.87	$ 0.26	$ 0.49