ACQUISITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE AND DISPOSITIONS - Acquisitions (Details) - Acquisitions [Member] $ in Thousands	12 Months Ended
	Apr. 30, 2018 USD ($) ft² unit	Apr. 30, 2017 USD ($)
Acquisitions and development projects placed in service [Abstract]
Total acquisition costs	$ 373,050	$ 0
Form of consideration, cash	373,050
Investment allocation, land	54,098
Investment allocation, building	314,971
Investment allocation, intangible assets	3,981
Multi-Family Residential [Member] | 191 homes - Oxbo - St Paul, MN [Member]
Acquisitions and development projects placed in service [Abstract]
Total acquisition costs	61,500
Form of consideration, cash	61,500
Investment allocation, land	5,809
Investment allocation, building	54,910
Investment allocation, intangible assets	$ 781
Number of apartment units | unit	191
Area of real estate property | ft²	11,477
Multi-Family Residential [Member] | 500 homes - Park Place - Plymouth, MN [Member]
Acquisitions and development projects placed in service [Abstract]
Total acquisition costs	$ 92,250
Form of consideration, cash	92,250
Investment allocation, land	10,609
Investment allocation, building	80,711
Investment allocation, intangible assets	$ 930
Number of apartment units | unit	500
Multi-Family Residential [Member] | 274 homes - Dylan - Denver, CO [Member]
Acquisitions and development projects placed in service [Abstract]
Total acquisition costs	$ 90,600
Form of consideration, cash	90,600
Investment allocation, land	12,155
Investment allocation, building	77,249
Investment allocation, intangible assets	$ 1,196
Number of apartment units | unit	274
Multi-Family Residential [Member] | 390 homes - Westend - Denver, CO [Member]
Acquisitions and development projects placed in service [Abstract]
Total acquisition costs	$ 128,700
Form of consideration, cash	128,700
Investment allocation, land	25,525
Investment allocation, building	102,101
Investment allocation, intangible assets	$ 1,074
Number of apartment units | unit	390