QUARTERLY RESULTS OF CONSOLIDATED OPERATIONS (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
QUARTERLY RESULTS OF CONSOLIDATED OPERATIONS (unaudited) [Abstract]
Revenues	$ 54,344	$ 51,174	$ 50,609	$ 49,611	$ 48,523	$ 48,406	$ 46,346	$ 45,045	$ 205,738	$ 188,320	$ 179,321
Net income (loss) attributable to Investors Real Estate Trust	30,280	23,110	11,600	(21,643)	11,003	39,797	16,666	4,540	43,347	72,006	24,087
Net income (loss) available to common shareholders	$ 27,994	$ 19,172	$ 8,722	$ (24,522)	$ 8,125	$ 36,918	$ 13,788	$ 1,661	$ 31,366	$ 60,492	$ 12,573
Net income (loss) per common share - basic & diluted (in dollars per share)	$ 0.23	$ 0.16	$ 0.07	$ (0.20)	$ 0.07	$ 0.30	$ 0.11	$ 0.01	$ 0.26	$ 0.49	$ 0.11