ACQUISITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE AND DISPOSITIONS - Property Dispositions (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2018 USD ($) ft² unit	Jan. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Jul. 31, 2017 USD ($)	Apr. 30, 2017 USD ($) ft² property	Jan. 31, 2017 USD ($)	Oct. 31, 2016 USD ($)	Jul. 31, 2016 USD ($)	Apr. 30, 2018 USD ($) ft² property unit	Apr. 30, 2017 USD ($) ft² property	Apr. 30, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price	$ 44,185	$ 42,716	$ 41,866	$ 40,978	$ 42,811	$ 39,797	$ 39,195	$ 38,301	$ 169,745	$ 160,104	$ 145,500
Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									515,130	286,926
Gain/(Loss)									$ 184,268	74,949
Multi-Family Residential [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property									15
Sales price									$ 18,913
Gain/(Loss)									3,343
Multi-Family Residential [Member] | Disposed of by Sale [Member] | Multifamily 327 Unit Minot Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									12,263
Gain/(Loss)									$ 701
Number of apartment units, dispositions | unit	327								327
Multi-Family Residential [Member] | Disposed of by Sale [Member] | Crown - Rochester, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 5,700
Gain/(Loss)									$ 2,382
Number of apartment units, dispositions | unit	48								48
Multi-Family Residential [Member] | Disposed of by Sale [Member] | Northern Valley - Rochester, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 950
Gain/(Loss)									$ 260
Number of apartment units, dispositions | unit	16								16
Multi-Family Residential [Member] | Disposed of by Sale [Member] | Minot Southgate Retail - Minot, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred gain on sale of properties	$ 626								$ 626
Multi-Family Residential [Member] | Disposed of by Sale [Member] | Pinecone Villas Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										3,540
Gain/(Loss)										$ 808
Number of apartment units, dispositions | property					24					24
Senior Housing Properties [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property									2
Healthcare [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property									28
Sales price										$ 265,736
Gain/(Loss)										$ 62,746
Healthcare [Member] | Disposed of by Sale [Member] | Idaho Spring Creek Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property										9
Sales price										$ 43,900
Gain/(Loss)										$ 6,503
Area of real estate property | ft²					189,244					189,244
Healthcare [Member] | Disposed of by Sale [Member] | Five Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property										5
Sales price										$ 69,928
Gain/(Loss)										$ 19,535
Area of real estate property | ft²					426,652					426,652
Healthcare [Member] | Disposed of by Sale [Member] | Wyoming Senior Housing Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property										5
Sales price										$ 49,600
Gain/(Loss)										$ 4,131
Area of real estate property | ft²					286,854					286,854
Healthcare [Member] | Disposed of by Sale [Member] | Nine Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property										9
Sales price										$ 30,700
Gain/(Loss)										$ 6,619
Area of real estate property | ft²					169,001					169,001
Healthcare [Member] | Disposed of by Sale [Member] | Four Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property										4
Sales price										$ 35,348
Gain/(Loss)										$ 20,837
Area of real estate property | ft²					169,562					169,562
Healthcare [Member] | Disposed of by Sale [Member] | Healtheast St John And Woodwinds Maplewood And Woodbury Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										$ 20,700
Gain/(Loss)										$ 6,923
Area of real estate property | ft²					114,316					114,316
Healthcare [Member] | Disposed of by Sale [Member] | Sartell 2000 23 Rd Street South Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										$ 5,600
Gain/(Loss)										$ (323)
Area of real estate property | ft²					59,760					59,760
Healthcare [Member] | Disposed of by Sale [Member] | Legends At Heritage Place Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										$ 9,960
Gain/(Loss)										$ (1,479)
Area of real estate property | ft²					98,174					98,174
Retail Site [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property									5
Unimproved Land [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property									2
Unimproved Land [Member] | Disposed of by Sale [Member] | Bismarck 4916 - Bismarck, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 3,175
Gain/(Loss)									(13)
Unimproved Land [Member] | Disposed of by Sale [Member] | Grand Chute, Wisconsin, Unimproved Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										$ 250
Gain/(Loss)										(24)
Other [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									493,042	17,400
Gain/(Loss)									180,938	11,419
Other [Member] | Disposed of by Sale [Member] | Minot Southgate Retail - Minot, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									3,440
Gain/(Loss)									$ 108
Area of real estate property | ft²	4,998								4,998
Other [Member] | Disposed of by Sale [Member] | Lexington Commerce Center Eagan Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 9,000
Gain/(Loss)									$ 5,037
Area of real estate property | ft²	90,260								90,260
Other [Member] | Disposed of by Sale [Member] | Eagan 1440 Duckwood Medical - Eagan, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 2,100
Gain/(Loss)									$ 214
Area of real estate property | ft²	17,640								17,640
Other [Member] | Disposed of by Sale [Member] | Edgewood Vista Hermantown Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 36,884
Gain/(Loss)									$ 12,187
Area of real estate property | ft²	279,834								279,834
Other [Member] | Disposed of by Sale [Member] | Urbandale - Urbandale IA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 16,700
Gain/(Loss)									$ 3,843
Area of real estate property | ft²	518,161								518,161
Other [Member] | Disposed of by Sale [Member] | Long Lake Road - Roseville MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 18,650
Gain/(Loss)									$ 5,884
Area of real estate property | ft²	36,053								36,053
Other [Member] | Disposed of by Sale [Member] | Healthcare Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 370,268
Gain/(Loss)									$ 137,490
Area of real estate property | ft²	1,205,432								1,205,432
Deposits held in escrow	$ 2,500								$ 2,500
Other [Member] | Disposed of by Sale [Member] | Garden View - St. Paul MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									14,000
Gain/(Loss)									$ 7,809
Area of real estate property | ft²	43,404								43,404
Other [Member] | Disposed of by Sale [Member] | Ritchie Medical - St. Paul MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 16,500
Gain/(Loss)									$ 6,081
Area of real estate property | ft²	52,116								52,116
Other [Member] | Disposed of by Sale [Member] | Bismarck 715 East Broadway - Bismarck, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price									$ 5,500
Gain/(Loss)									$ 2,285
Area of real estate property | ft²	22,187								22,187
Other [Member] | Disposed of by Sale [Member] | Stone Container Fargo Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										13,400
Gain/(Loss)										$ 8,982
Area of real estate property | ft²					195,075					195,075
Other [Member] | Disposed of by Sale [Member] | Grand Forks Carmike Grand Forks Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price										$ 4,000
Gain/(Loss)										$ 2,437
Area of real estate property | ft²					28,528					28,528
Real Estate [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									$ 73,034	$ 64,326	$ 58,148
Real Estate [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									330,862	211,977
Real Estate [Member] | Multi-Family Residential [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									15,570
Real Estate [Member] | Multi-Family Residential [Member] | Disposed of by Sale [Member] | Multifamily 327 Unit Minot Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									11,562
Real Estate [Member] | Multi-Family Residential [Member] | Disposed of by Sale [Member] | Crown - Rochester, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									3,318
Real Estate [Member] | Multi-Family Residential [Member] | Disposed of by Sale [Member] | Northern Valley - Rochester, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									690
Real Estate [Member] | Multi-Family Residential [Member] | Disposed of by Sale [Member] | Pinecone Villas Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										2,732
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										202,990
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Idaho Spring Creek Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										37,397
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Five Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										50,393
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Wyoming Senior Housing Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										45,469
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Nine Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										24,081
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Four Edgewood Vista Senior Housing Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										14,511
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Healtheast St John And Woodwinds Maplewood And Woodbury Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										13,777
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Sartell 2000 23 Rd Street South Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										5,923
Real Estate [Member] | Healthcare [Member] | Disposed of by Sale [Member] | Legends At Heritage Place Sartell Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										11,439
Real Estate [Member] | Unimproved Land [Member] | Disposed of by Sale [Member] | Bismarck 4916 - Bismarck, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									3,188
Real Estate [Member] | Unimproved Land [Member] | Disposed of by Sale [Member] | Grand Chute, Wisconsin, Unimproved Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										274
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									312,104	5,981
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Minot Southgate Retail - Minot, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									3,332
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Lexington Commerce Center Eagan Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									3,963
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Eagan 1440 Duckwood Medical - Eagan, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									1,886
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Edgewood Vista Hermantown Mn [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									24,697
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Urbandale - Urbandale IA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									12,857
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Long Lake Road - Roseville MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									12,766
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Healthcare Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									232,778
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Garden View - St. Paul MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									6,191
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Ritchie Medical - St. Paul MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									10,419
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Bismarck 715 East Broadway - Bismarck, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue									$ 3,215
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Stone Container Fargo Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										4,418
Real Estate [Member] | Other [Member] | Disposed of by Sale [Member] | Grand Forks Carmike Grand Forks Nd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of revenue										$ 1,563