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SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Gross amount at which carries at close of period [Abstract]    
Accumulated Depreciation $ (443,592) $ (399,249)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Total real estate investments 1,870,854 1,437,969
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]    
Balance at beginning of year 399,249 349,122
Additions during year [Abstract]    
Provisions for depreciation 78,268 72,051
Deductions during year [Abstract]    
Accumulated depreciation on real estate sold or classified as held for sale (24,161) (21,440)
Other (9,764) (484)
Balance at close of year 443,592 399,249
Net basis of real estate investments for federal income tax purposes 1,800,000 1,400,000
Unimproved Land    
Gross amount at which carries at close of period [Abstract]    
Total 0 0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at beginning of year 0 1,376
Cost of real estate sold 0 (1,376)
Balance at close of year 0 0
Total real estate investments 1,827,578 1,413,308
Wholly Owned Properties    
Gross amount at which carries at close of period [Abstract]    
Total 2,271,170 1,812,557
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at beginning of year 1,812,557 1,643,078
Improvements and Other 34,427 27,460
Total additions 2,338,632 1,852,309
Cost of real estate sold (57,698) (38,111)
Other (9,764) (1,641)
Balance at close of year 2,271,170 1,812,557
Multifamily    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 262,673  
Initial Cost to Company [Abstract]    
Land 129,597  
Buildings & Improvements 1,258,137  
Costs capitalized subsequent to acquisition 180,716  
Gross amount at which carries at close of period [Abstract]    
Land 146,004  
Buildings & Improvements 1,422,446  
Total 1,568,450  
Accumulated Depreciation (419,730)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 1,568,450  
Deductions during year [Abstract]    
Balance at close of year 419,730  
Multifamily | 71 France - Edina, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 52,149  
Initial Cost to Company [Abstract]    
Land 4,721  
Buildings & Improvements 61,762  
Costs capitalized subsequent to acquisition 625  
Gross amount at which carries at close of period [Abstract]    
Land 4,801  
Buildings & Improvements 62,307  
Total 67,108  
Accumulated Depreciation (17,093)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 67,108  
Deductions during year [Abstract]    
Balance at close of year 17,093  
Multifamily | Alps Park - Rapid City, SD    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 287  
Buildings & Improvements 5,551  
Costs capitalized subsequent to acquisition 691  
Gross amount at which carries at close of period [Abstract]    
Land 336  
Buildings & Improvements 6,193  
Total 6,529  
Accumulated Depreciation (1,817)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 6,529  
Deductions during year [Abstract]    
Balance at close of year 1,817  
Multifamily | Arcata - Golden Valley, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 2,088  
Buildings & Improvements 31,036  
Costs capitalized subsequent to acquisition 413  
Gross amount at which carries at close of period [Abstract]    
Land 2,128  
Buildings & Improvements 31,409  
Total 33,537  
Accumulated Depreciation (9,627)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 33,537  
Deductions during year [Abstract]    
Balance at close of year 9,627  
Multifamily | Ashland - Grand Forks, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 741  
Buildings & Improvements 7,569  
Costs capitalized subsequent to acquisition 364  
Gross amount at which carries at close of period [Abstract]    
Land 823  
Buildings & Improvements 7,851  
Total 8,674  
Accumulated Depreciation (2,688)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 8,674  
Deductions during year [Abstract]    
Balance at close of year 2,688  
Multifamily | Avalon Cove - Rochester, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,616  
Buildings & Improvements 34,074  
Costs capitalized subsequent to acquisition 825  
Gross amount at which carries at close of period [Abstract]    
Land 1,808  
Buildings & Improvements 34,707  
Total 36,515  
Accumulated Depreciation (7,327)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 36,515  
Deductions during year [Abstract]    
Balance at close of year 7,327  
Multifamily | Boulder Court - Eagan, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,067  
Buildings & Improvements 5,498  
Costs capitalized subsequent to acquisition 3,124  
Gross amount at which carries at close of period [Abstract]    
Land 1,576  
Buildings & Improvements 8,113  
Total 9,689  
Accumulated Depreciation (4,590)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 9,689  
Deductions during year [Abstract]    
Balance at close of year 4,590  
Multifamily | Canyon Lake - Rapid City, SD    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 305  
Buildings & Improvements 3,958  
Costs capitalized subsequent to acquisition 2,285  
Gross amount at which carries at close of period [Abstract]    
Land 420  
Buildings & Improvements 6,128  
Total 6,548  
Accumulated Depreciation (3,287)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 6,548  
Deductions during year [Abstract]    
Balance at close of year 3,287  
Multifamily | Cardinal Point - Grand Forks, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,600  
Buildings & Improvements 33,400  
Costs capitalized subsequent to acquisition 400  
Gross amount at which carries at close of period [Abstract]    
Land 1,727  
Buildings & Improvements 33,673  
Total 35,400  
Accumulated Depreciation (4,132)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 35,400  
Deductions during year [Abstract]    
Balance at close of year 4,132  
Multifamily | Castlerock - Billings, MT    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 736  
Buildings & Improvements 4,864  
Costs capitalized subsequent to acquisition 2,257  
Gross amount at which carries at close of period [Abstract]    
Land 1,045  
Buildings & Improvements 6,812  
Total 7,857  
Accumulated Depreciation (4,582)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 7,857  
Deductions during year [Abstract]    
Balance at close of year 4,582  
Multifamily | Chateau - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 301  
Buildings & Improvements 20,058  
Costs capitalized subsequent to acquisition 1,185  
Gross amount at which carries at close of period [Abstract]    
Land 326  
Buildings & Improvements 21,218  
Total 21,544  
Accumulated Depreciation (6,880)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 21,544  
Deductions during year [Abstract]    
Balance at close of year 6,880  
Multifamily | Cimarron Hills - Omaha, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 8,700  
Initial Cost to Company [Abstract]    
Land 706  
Buildings & Improvements 9,588  
Costs capitalized subsequent to acquisition 4,684  
Gross amount at which carries at close of period [Abstract]    
Land 1,639  
Buildings & Improvements 13,339  
Total 14,978  
Accumulated Depreciation (7,998)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 14,978  
Deductions during year [Abstract]    
Balance at close of year 7,998  
Multifamily | Commons and Landing at Southgate - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 5,945  
Buildings & Improvements 47,512  
Costs capitalized subsequent to acquisition 2,448  
Gross amount at which carries at close of period [Abstract]    
Land 6,424  
Buildings & Improvements 49,481  
Total 55,905  
Accumulated Depreciation (15,690)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 55,905  
Deductions during year [Abstract]    
Balance at close of year 15,690  
Multifamily | Connelly on Eleven - Burnsville, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 2,401  
Buildings & Improvements 11,515  
Costs capitalized subsequent to acquisition 16,010  
Gross amount at which carries at close of period [Abstract]    
Land 3,206  
Buildings & Improvements 26,720  
Total 29,926  
Accumulated Depreciation (14,315)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 29,926  
Deductions during year [Abstract]    
Balance at close of year 14,315  
Multifamily | Cottonwood - Bismarck, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,056  
Buildings & Improvements 17,372  
Costs capitalized subsequent to acquisition 5,799  
Gross amount at which carries at close of period [Abstract]    
Land 1,962  
Buildings & Improvements 22,265  
Total 24,227  
Accumulated Depreciation (13,046)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 24,227  
Deductions during year [Abstract]    
Balance at close of year 13,046  
Multifamily | Country Meadows - Billings, MT    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 491  
Buildings & Improvements 7,809  
Costs capitalized subsequent to acquisition 1,623  
Gross amount at which carries at close of period [Abstract]    
Land 599  
Buildings & Improvements 9,324  
Total 9,923  
Accumulated Depreciation (5,872)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 9,923  
Deductions during year [Abstract]    
Balance at close of year 5,872  
Multifamily | Cypress Court - St. Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 11,338  
Initial Cost to Company [Abstract]    
Land 1,583  
Buildings & Improvements 18,879  
Costs capitalized subsequent to acquisition 545  
Gross amount at which carries at close of period [Abstract]    
Land 1,625  
Buildings & Improvements 19,382  
Total 21,007  
Accumulated Depreciation (5,995)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 21,007  
Deductions during year [Abstract]    
Balance at close of year 5,995  
Multifamily | Deer Ridge - Jamestown, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 711  
Buildings & Improvements 24,129  
Costs capitalized subsequent to acquisition 348  
Gross amount at which carries at close of period [Abstract]    
Land 785  
Buildings & Improvements 24,403  
Total 25,188  
Accumulated Depreciation (7,292)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 25,188  
Deductions during year [Abstract]    
Balance at close of year 7,292  
Multifamily | Donovan - Lincoln, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 11,270  
Initial Cost to Company [Abstract]    
Land 1,515  
Buildings & Improvements 15,730  
Costs capitalized subsequent to acquisition 4,952  
Gross amount at which carries at close of period [Abstract]    
Land 1,817  
Buildings & Improvements 20,380  
Total 22,197  
Accumulated Depreciation (6,531)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 22,197  
Deductions during year [Abstract]    
Balance at close of year 6,531  
Multifamily | Dylan - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 12,155  
Buildings & Improvements 77,215  
Costs capitalized subsequent to acquisition 1,138  
Gross amount at which carries at close of period [Abstract]    
Land 12,241  
Buildings & Improvements 78,267  
Total 90,508  
Accumulated Depreciation $ (10,892)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 90,508  
Deductions during year [Abstract]    
Balance at close of year 10,892  
Multifamily | Evergreen - Isanti, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,129  
Buildings & Improvements 5,524  
Costs capitalized subsequent to acquisition 628  
Gross amount at which carries at close of period [Abstract]    
Land 1,159  
Buildings & Improvements 6,122  
Total 7,281  
Accumulated Depreciation (2,290)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 7,281  
Deductions during year [Abstract]    
Balance at close of year 2,290  
Multifamily | Freightyard - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,889  
Buildings & Improvements 23,616  
Costs capitalized subsequent to acquisition 1,296  
Gross amount at which carries at close of period [Abstract]    
Land 1,895  
Buildings & Improvements 24,906  
Total 26,801  
Accumulated Depreciation $ (2,091)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 26,801  
Deductions during year [Abstract]    
Balance at close of year 2,091  
Multifamily | Gardens - Grand Forks, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 518  
Buildings & Improvements 8,702  
Costs capitalized subsequent to acquisition 141  
Gross amount at which carries at close of period [Abstract]    
Land 535  
Buildings & Improvements 8,826  
Total 9,361  
Accumulated Depreciation (2,100)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 9,361  
Deductions during year [Abstract]    
Balance at close of year 2,100  
Multifamily | Grand Gateway - St. Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 814  
Buildings & Improvements 7,086  
Costs capitalized subsequent to acquisition 2,152  
Gross amount at which carries at close of period [Abstract]    
Land 970  
Buildings & Improvements 9,082  
Total 10,052  
Accumulated Depreciation (3,972)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 10,052  
Deductions during year [Abstract]    
Balance at close of year 3,972  
Multifamily | GrandeVille Shores - Rochester, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 46,320  
Initial Cost to Company [Abstract]    
Land 6,588  
Buildings & Improvements 67,072  
Costs capitalized subsequent to acquisition 5,741  
Gross amount at which carries at close of period [Abstract]    
Land 6,776  
Buildings & Improvements 72,625  
Total 79,401  
Accumulated Depreciation (16,311)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 79,401  
Deductions during year [Abstract]    
Balance at close of year 16,311  
Multifamily | Greenfield - Omaha, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 578  
Buildings & Improvements 4,122  
Costs capitalized subsequent to acquisition 3,007  
Gross amount at which carries at close of period [Abstract]    
Land 876  
Buildings & Improvements 6,831  
Total 7,707  
Accumulated Depreciation (2,769)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 7,707  
Deductions during year [Abstract]    
Balance at close of year 2,769  
Multifamily | Homestead Garden - Rapid City, SD    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 655  
Buildings & Improvements 14,139  
Costs capitalized subsequent to acquisition 1,219  
Gross amount at which carries at close of period [Abstract]    
Land 792  
Buildings & Improvements 15,221  
Total 16,013  
Accumulated Depreciation (3,944)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 16,013  
Deductions during year [Abstract]    
Balance at close of year 3,944  
Multifamily | Lakeside Village - Lincoln, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 11,158  
Initial Cost to Company [Abstract]    
Land 1,215  
Buildings & Improvements 15,837  
Costs capitalized subsequent to acquisition 3,369  
Gross amount at which carries at close of period [Abstract]    
Land 1,476  
Buildings & Improvements 18,945  
Total 20,421  
Accumulated Depreciation (6,098)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 20,421  
Deductions during year [Abstract]    
Balance at close of year 6,098  
Multifamily | Legacy - Grand Forks, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,362  
Buildings & Improvements 21,727  
Costs capitalized subsequent to acquisition 10,958  
Gross amount at which carries at close of period [Abstract]    
Land 2,474  
Buildings & Improvements 31,573  
Total 34,047  
Accumulated Depreciation (19,735)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 34,047  
Deductions during year [Abstract]    
Balance at close of year 19,735  
Multifamily | Legacy Heights - Bismarck, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,207  
Buildings & Improvements 13,742  
Costs capitalized subsequent to acquisition 290  
Gross amount at which carries at close of period [Abstract]    
Land 1,142  
Buildings & Improvements 14,097  
Total 15,239  
Accumulated Depreciation (3,102)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 15,239  
Deductions during year [Abstract]    
Balance at close of year 3,102  
Multifamily | Lugano at Cherry Creek - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 7,679  
Buildings & Improvements 87,766  
Costs capitalized subsequent to acquisition 1,317  
Gross amount at which carries at close of period [Abstract]    
Land 7,679  
Buildings & Improvements 89,083  
Total 96,762  
Accumulated Depreciation $ (7,670)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 96,762  
Deductions during year [Abstract]    
Balance at close of year 7,670  
Multifamily | Meadows - Jamestown, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 590  
Buildings & Improvements 4,519  
Costs capitalized subsequent to acquisition 2,075  
Gross amount at which carries at close of period [Abstract]    
Land 730  
Buildings & Improvements 6,454  
Total 7,184  
Accumulated Depreciation (4,101)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 7,184  
Deductions during year [Abstract]    
Balance at close of year 4,101  
Multifamily | Monticello Crossings - Monticello, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,734  
Buildings & Improvements 30,136  
Costs capitalized subsequent to acquisition 649  
Gross amount at which carries at close of period [Abstract]    
Land 1,951  
Buildings & Improvements 30,568  
Total 32,519  
Accumulated Depreciation (6,660)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 32,519  
Deductions during year [Abstract]    
Balance at close of year 6,660  
Multifamily | Monticello Village - Monticello, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 490  
Buildings & Improvements 3,756  
Costs capitalized subsequent to acquisition 1,211  
Gross amount at which carries at close of period [Abstract]    
Land 655  
Buildings & Improvements 4,802  
Total 5,457  
Accumulated Depreciation (2,655)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 5,457  
Deductions during year [Abstract]    
Balance at close of year 2,655  
Multifamily | Northridge - Bismarck, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 884  
Buildings & Improvements 7,515  
Costs capitalized subsequent to acquisition 296  
Gross amount at which carries at close of period [Abstract]    
Land 1,048  
Buildings & Improvements 7,647  
Total 8,695  
Accumulated Depreciation (1,912)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 8,695  
Deductions during year [Abstract]    
Balance at close of year 1,912  
Multifamily | Olympic Village - Billings, MT    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,164  
Buildings & Improvements 10,441  
Costs capitalized subsequent to acquisition 4,047  
Gross amount at which carries at close of period [Abstract]    
Land 1,885  
Buildings & Improvements 13,767  
Total 15,652  
Accumulated Depreciation (8,539)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 15,652  
Deductions during year [Abstract]    
Balance at close of year 8,539  
Multifamily | Oxbo - St Paul, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 5,809  
Buildings & Improvements 51,586  
Costs capitalized subsequent to acquisition 263  
Gross amount at which carries at close of period [Abstract]    
Land 5,822  
Buildings & Improvements 51,836  
Total 57,658  
Accumulated Depreciation $ (8,896)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 57,658  
Deductions during year [Abstract]    
Balance at close of year 8,896  
Multifamily | Park Meadows - Waite Park, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 1,143  
Buildings & Improvements 9,099  
Costs capitalized subsequent to acquisition 9,976  
Gross amount at which carries at close of period [Abstract]    
Land 2,140  
Buildings & Improvements 18,078  
Total 20,218  
Accumulated Depreciation (13,170)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 20,218  
Deductions during year [Abstract]    
Balance at close of year 13,170  
Multifamily | Park Place - Plymouth, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 10,609  
Buildings & Improvements 80,781  
Costs capitalized subsequent to acquisition 13,587  
Gross amount at which carries at close of period [Abstract]    
Land 10,819  
Buildings & Improvements 94,158  
Total 104,977  
Accumulated Depreciation $ (15,767)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 104,977  
Deductions during year [Abstract]    
Balance at close of year 15,767  
Multifamily | Plaza - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 867  
Buildings & Improvements 12,784  
Costs capitalized subsequent to acquisition 3,118  
Gross amount at which carries at close of period [Abstract]    
Land 1,011  
Buildings & Improvements 15,758  
Total 16,769  
Accumulated Depreciation (6,270)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 16,769  
Deductions during year [Abstract]    
Balance at close of year 6,270  
Multifamily | Pointe West - Rapid City, SD    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 240  
Buildings & Improvements 3,538  
Costs capitalized subsequent to acquisition 2,209  
Gross amount at which carries at close of period [Abstract]    
Land 463  
Buildings & Improvements 5,524  
Total 5,987  
Accumulated Depreciation (4,044)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 5,987  
Deductions during year [Abstract]    
Balance at close of year 4,044  
Multifamily | Ponds at Heritage Place - Sartell, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 395  
Buildings & Improvements 4,564  
Costs capitalized subsequent to acquisition 540  
Gross amount at which carries at close of period [Abstract]    
Land 419  
Buildings & Improvements 5,080  
Total 5,499  
Accumulated Depreciation (1,773)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 5,499  
Deductions during year [Abstract]    
Balance at close of year 1,773  
Multifamily | Quarry Ridge - Rochester, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 23,409  
Initial Cost to Company [Abstract]    
Land 2,254  
Buildings & Improvements 30,024  
Costs capitalized subsequent to acquisition 5,223  
Gross amount at which carries at close of period [Abstract]    
Land 2,412  
Buildings & Improvements 35,089  
Total 37,501  
Accumulated Depreciation (12,114)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 37,501  
Deductions during year [Abstract]    
Balance at close of year 12,114  
Multifamily | Red 20 - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 20,775  
Initial Cost to Company [Abstract]    
Land 1,900  
Buildings & Improvements 24,116  
Costs capitalized subsequent to acquisition 521  
Gross amount at which carries at close of period [Abstract]    
Land 1,908  
Buildings & Improvements 24,629  
Total 26,537  
Accumulated Depreciation (7,560)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 26,537  
Deductions during year [Abstract]    
Balance at close of year 7,560  
Multifamily | Regency Park Estates - St. Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 7,167  
Initial Cost to Company [Abstract]    
Land 702  
Buildings & Improvements 10,198  
Costs capitalized subsequent to acquisition 6,155  
Gross amount at which carries at close of period [Abstract]    
Land 1,179  
Buildings & Improvements 15,876  
Total 17,055  
Accumulated Depreciation (5,205)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 17,055  
Deductions during year [Abstract]    
Balance at close of year 5,205  
Multifamily | Rimrock West - Billings, MT    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 330  
Buildings & Improvements 3,489  
Costs capitalized subsequent to acquisition 2,044  
Gross amount at which carries at close of period [Abstract]    
Land 568  
Buildings & Improvements 5,295  
Total 5,863  
Accumulated Depreciation (3,403)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 5,863  
Deductions during year [Abstract]    
Balance at close of year 3,403  
Multifamily | River Ridge - Bismarck, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 576  
Buildings & Improvements 24,670  
Costs capitalized subsequent to acquisition 1,154  
Gross amount at which carries at close of period [Abstract]    
Land 922  
Buildings & Improvements 25,478  
Total 26,400  
Accumulated Depreciation (9,018)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 26,400  
Deductions during year [Abstract]    
Balance at close of year 9,018  
Multifamily | Rocky Meadows - Billings, MT    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 656  
Buildings & Improvements 5,726  
Costs capitalized subsequent to acquisition 1,632  
Gross amount at which carries at close of period [Abstract]    
Land 840  
Buildings & Improvements 7,174  
Total 8,014  
Accumulated Depreciation (4,817)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 8,014  
Deductions during year [Abstract]    
Balance at close of year 4,817  
Multifamily | Rum River - Isanti, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 843  
Buildings & Improvements 4,823  
Costs capitalized subsequent to acquisition 515  
Gross amount at which carries at close of period [Abstract]    
Land 870  
Buildings & Improvements 5,311  
Total 6,181  
Accumulated Depreciation (2,358)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 6,181  
Deductions during year [Abstract]    
Balance at close of year 2,358  
Multifamily | Silver Springs - Rapid City, SD    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 215  
Buildings & Improvements 3,007  
Costs capitalized subsequent to acquisition 1,077  
Gross amount at which carries at close of period [Abstract]    
Land 273  
Buildings & Improvements 4,026  
Total 4,299  
Accumulated Depreciation (1,142)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 4,299  
Deductions during year [Abstract]    
Balance at close of year 1,142  
Multifamily | South Pointe - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 550  
Buildings & Improvements 9,548  
Costs capitalized subsequent to acquisition 5,814  
Gross amount at which carries at close of period [Abstract]    
Land 1,489  
Buildings & Improvements 14,423  
Total 15,912  
Accumulated Depreciation (10,819)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 15,912  
Deductions during year [Abstract]    
Balance at close of year 10,819  
Multifamily | Southpoint - Grand Forks, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 576  
Buildings & Improvements 9,893  
Costs capitalized subsequent to acquisition 284  
Gross amount at which carries at close of period [Abstract]    
Land 663  
Buildings & Improvements 10,090  
Total 10,753  
Accumulated Depreciation (2,696)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 10,753  
Deductions during year [Abstract]    
Balance at close of year 2,696  
Multifamily | Southfork - Lakeville, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 21,675  
Initial Cost to Company [Abstract]    
Land 3,502  
Buildings & Improvements 40,153  
Costs capitalized subsequent to acquisition 8,626  
Gross amount at which carries at close of period [Abstract]    
Land 3,583  
Buildings & Improvements 48,698  
Total 52,281  
Accumulated Depreciation $ (6,292)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 52,281  
Deductions during year [Abstract]    
Balance at close of year 6,292  
Multifamily | Sunset Trail - Rochester, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 336  
Buildings & Improvements 12,814  
Costs capitalized subsequent to acquisition 3,429  
Gross amount at which carries at close of period [Abstract]    
Land 826  
Buildings & Improvements 15,753  
Total 16,579  
Accumulated Depreciation (9,579)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 16,579  
Deductions during year [Abstract]    
Balance at close of year 9,579  
Multifamily | Thomasbrook - Lincoln, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 13,100  
Initial Cost to Company [Abstract]    
Land 600  
Buildings & Improvements 10,306  
Costs capitalized subsequent to acquisition 5,474  
Gross amount at which carries at close of period [Abstract]    
Land 1,710  
Buildings & Improvements 14,670  
Total 16,380  
Accumulated Depreciation (9,080)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 16,380  
Deductions during year [Abstract]    
Balance at close of year 9,080  
Multifamily | West Stonehill - Waite Park, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 16,425  
Initial Cost to Company [Abstract]    
Land 939  
Buildings & Improvements 10,167  
Costs capitalized subsequent to acquisition 10,933  
Gross amount at which carries at close of period [Abstract]    
Land 1,912  
Buildings & Improvements 20,127  
Total 22,039  
Accumulated Depreciation (12,812)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 22,039  
Deductions during year [Abstract]    
Balance at close of year 12,812  
Multifamily | Westend - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 25,525  
Buildings & Improvements 102,180  
Costs capitalized subsequent to acquisition 935  
Gross amount at which carries at close of period [Abstract]    
Land 25,532  
Buildings & Improvements 103,108  
Total 128,640  
Accumulated Depreciation $ (13,525)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 128,640  
Deductions during year [Abstract]    
Balance at close of year 13,525  
Multifamily | Whispering Ridge - Omaha, NE    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 19,187  
Initial Cost to Company [Abstract]    
Land 2,139  
Buildings & Improvements 25,424  
Costs capitalized subsequent to acquisition 3,715  
Gross amount at which carries at close of period [Abstract]    
Land 2,551  
Buildings & Improvements 28,727  
Total 31,278  
Accumulated Depreciation (9,162)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 31,278  
Deductions during year [Abstract]    
Balance at close of year 9,162  
Multifamily | Woodridge - Rochester, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 370  
Buildings & Improvements 6,028  
Costs capitalized subsequent to acquisition 5,380  
Gross amount at which carries at close of period [Abstract]    
Land 761  
Buildings & Improvements 11,017  
Total 11,778  
Accumulated Depreciation (6,625)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 11,778  
Deductions during year [Abstract]    
Balance at close of year $ 6,625  
Multifamily | Minimum | 71 France - Edina, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Alps Park - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Ashland - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Avalon Cove - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Boulder Court - Eagan, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Canyon Lake - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Cardinal Point - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Castlerock - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Chateau - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Cimarron Hills - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Commons and Landing at Southgate - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Connelly on Eleven - Burnsville, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Cottonwood - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Country Meadows - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Cypress Court - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Deer Ridge - Jamestown, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Donovan - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Evergreen - Isanti, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Gardens - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Grand Gateway - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | GrandeVille Shores - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Greenfield - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Homestead Garden - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Lakeside Village - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Legacy - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Legacy Heights - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Meadows - Jamestown, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Monticello Crossings - Monticello, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Monticello Village - Monticello, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Northridge - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Olympic Village - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Park Meadows - Waite Park, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Plaza - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Pointe West - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Ponds at Heritage Place - Sartell, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Quarry Ridge - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Red 20 - Minneapolis, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Regency Park Estates - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Rimrock West - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | River Ridge - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Rocky Meadows - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Rum River - Isanti, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Silver Springs - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | South Pointe - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Southpoint - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Sunset Trail - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Thomasbrook - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | West Stonehill - Waite Park, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Whispering Ridge - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Minimum | Woodridge - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Multifamily | Maximum | 71 France - Edina, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Alps Park - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Ashland - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Avalon Cove - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Boulder Court - Eagan, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Canyon Lake - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Cardinal Point - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Castlerock - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Chateau - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Cimarron Hills - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Commons and Landing at Southgate - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Connelly on Eleven - Burnsville, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Cottonwood - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Country Meadows - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Cypress Court - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Deer Ridge - Jamestown, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Donovan - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Evergreen - Isanti, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Gardens - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Grand Gateway - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | GrandeVille Shores - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Greenfield - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Homestead Garden - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Lakeside Village - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Legacy - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Legacy Heights - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Meadows - Jamestown, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Monticello Crossings - Monticello, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Monticello Village - Monticello, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Northridge - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Olympic Village - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Park Meadows - Waite Park, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Plaza - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Pointe West - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Ponds at Heritage Place - Sartell, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Quarry Ridge - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Red 20 - Minneapolis, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Regency Park Estates - St. Cloud, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Rimrock West - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | River Ridge - Bismarck, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Rocky Meadows - Billings, MT    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Rum River - Isanti, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Silver Springs - Rapid City, SD    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | South Pointe - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Southpoint - Grand Forks, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Sunset Trail - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Thomasbrook - Lincoln, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | West Stonehill - Waite Park, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Whispering Ridge - Omaha, NE    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Maximum | Woodridge - Rochester, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Multifamily | Wholly Owned Properties    
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Multifamily and Other $ 491,648 $ 181,771
MultiFamily Non-Same-Store    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 221,110  
Initial Cost to Company [Abstract]    
Land 64,385  
Buildings & Improvements 600,150  
Costs capitalized subsequent to acquisition 11,264  
Gross amount at which carries at close of period [Abstract]    
Land 65,359  
Buildings & Improvements 610,440  
Total 675,799  
Accumulated Depreciation (16,273)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 675,799  
Deductions during year [Abstract]    
Balance at close of year 16,273  
MultiFamily Non-Same-Store | Bayberry Place - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 11,048  
Initial Cost to Company [Abstract]    
Land 1,807  
Buildings & Improvements 14,113  
Costs capitalized subsequent to acquisition 538  
Gross amount at which carries at close of period [Abstract]    
Land 1,865  
Buildings & Improvements 14,593  
Total 16,458  
Accumulated Depreciation $ (177)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 16,458  
Deductions during year [Abstract]    
Balance at close of year 177  
MultiFamily Non-Same-Store | Burgundy and Hillsboro Court - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 23,570  
Initial Cost to Company [Abstract]    
Land 2,834  
Buildings & Improvements 31,149  
Costs capitalized subsequent to acquisition 1,177  
Gross amount at which carries at close of period [Abstract]    
Land 2,913  
Buildings & Improvements 32,247  
Total 35,160  
Accumulated Depreciation $ (398)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 35,160  
Deductions during year [Abstract]    
Balance at close of year 398  
MultiFamily Non-Same-Store | Civic Lofts - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 6,166  
Buildings & Improvements 55,182  
Costs capitalized subsequent to acquisition 51  
Gross amount at which carries at close of period [Abstract]    
Land 6,171  
Buildings & Improvements 55,228  
Total 61,399  
Accumulated Depreciation $ (148)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 61,399  
Deductions during year [Abstract]    
Balance at close of year 148  
MultiFamily Non-Same-Store | Gatewood - St Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 5,156  
Initial Cost to Company [Abstract]    
Land 327  
Buildings & Improvements 6,858  
Costs capitalized subsequent to acquisition 348  
Gross amount at which carries at close of period [Abstract]    
Land 342  
Buildings & Improvements 7,191  
Total 7,533  
Accumulated Depreciation $ (95)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 7,533  
Deductions during year [Abstract]    
Balance at close of year 95  
MultiFamily Non-Same-Store | Grove Ridge - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 7,992  
Initial Cost to Company [Abstract]    
Land 1,250  
Buildings & Improvements 10,271  
Costs capitalized subsequent to acquisition 405  
Gross amount at which carries at close of period [Abstract]    
Land 1,293  
Buildings & Improvements 10,633  
Total 11,926  
Accumulated Depreciation $ (133)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 11,926  
Deductions during year [Abstract]    
Balance at close of year 133  
MultiFamily Non-Same-Store | Ironwood - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 2,165  
Buildings & Improvements 36,874  
Costs capitalized subsequent to acquisition 238  
Gross amount at which carries at close of period [Abstract]    
Land 2,167  
Buildings & Improvements 37,110  
Total 39,277  
Accumulated Depreciation $ (2,564)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 39,277  
Deductions during year [Abstract]    
Balance at close of year 2,564  
MultiFamily Non-Same-Store | Legacy Waite Park - St Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 6,923  
Initial Cost to Company [Abstract]    
Land 412  
Buildings & Improvements 9,556  
Costs capitalized subsequent to acquisition 428  
Gross amount at which carries at close of period [Abstract]    
Land 426  
Buildings & Improvements 9,970  
Total 10,396  
Accumulated Depreciation $ (135)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 10,396  
Deductions during year [Abstract]    
Balance at close of year 135  
MultiFamily Non-Same-Store | New Hope Garden and Village - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 9,943  
Initial Cost to Company [Abstract]    
Land 1,603  
Buildings & Improvements 12,578  
Costs capitalized subsequent to acquisition 480  
Gross amount at which carries at close of period [Abstract]    
Land 1,651  
Buildings & Improvements 13,010  
Total 14,661  
Accumulated Depreciation $ (170)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 14,661  
Deductions during year [Abstract]    
Balance at close of year 170  
MultiFamily Non-Same-Store | Palisades - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 22,260  
Initial Cost to Company [Abstract]    
Land 6,919  
Buildings & Improvements 46,577  
Costs capitalized subsequent to acquisition 386  
Gross amount at which carries at close of period [Abstract]    
Land 6,959  
Buildings & Improvements 46,923  
Total 53,882  
Accumulated Depreciation $ (574)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 53,882  
Deductions during year [Abstract]    
Balance at close of year 574  
MultiFamily Non-Same-Store | Parkhouse - Thornton, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 10,474  
Buildings & Improvements 132,105  
Costs capitalized subsequent to acquisition 987  
Gross amount at which carries at close of period [Abstract]    
Land 10,484  
Buildings & Improvements 133,082  
Total 143,566  
Accumulated Depreciation $ (6,922)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 143,566  
Deductions during year [Abstract]    
Balance at close of year 6,922  
MultiFamily Non-Same-Store | Plymouth Pointe - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 9,575  
Initial Cost to Company [Abstract]    
Land 1,042  
Buildings & Improvements 12,810  
Costs capitalized subsequent to acquisition 526  
Gross amount at which carries at close of period [Abstract]    
Land 1,073  
Buildings & Improvements 13,305  
Total 14,378  
Accumulated Depreciation $ (174)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 14,378  
Deductions during year [Abstract]    
Balance at close of year 174  
MultiFamily Non-Same-Store | Pointe West St Cloud - St Cloud, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 5,008  
Initial Cost to Company [Abstract]    
Land 246  
Buildings & Improvements 6,850  
Costs capitalized subsequent to acquisition 437  
Gross amount at which carries at close of period [Abstract]    
Land 260  
Buildings & Improvements 7,273  
Total 7,533  
Accumulated Depreciation $ (98)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 7,533  
Deductions during year [Abstract]    
Balance at close of year 98  
MultiFamily Non-Same-Store | Portage - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 5,991  
Initial Cost to Company [Abstract]    
Land 2,133  
Buildings & Improvements 6,685  
Costs capitalized subsequent to acquisition 415  
Gross amount at which carries at close of period [Abstract]    
Land 2,226  
Buildings & Improvements 7,007  
Total 9,233  
Accumulated Depreciation $ (83)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 9,233  
Deductions during year [Abstract]    
Balance at close of year 83  
MultiFamily Non-Same-Store | River Pointe - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 25,412  
Initial Cost to Company [Abstract]    
Land 3,346  
Buildings & Improvements 33,118  
Costs capitalized subsequent to acquisition 951  
Gross amount at which carries at close of period [Abstract]    
Land 3,426  
Buildings & Improvements 33,989  
Total 37,415  
Accumulated Depreciation $ (422)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 37,415  
Deductions during year [Abstract]    
Balance at close of year 422  
MultiFamily Non-Same-Store | Southdale Parc - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 5,301  
Initial Cost to Company [Abstract]    
Land 1,569  
Buildings & Improvements 7,740  
Costs capitalized subsequent to acquisition 302  
Gross amount at which carries at close of period [Abstract]    
Land 1,618  
Buildings & Improvements 7,993  
Total 9,611  
Accumulated Depreciation $ (96)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 9,611  
Deductions during year [Abstract]    
Balance at close of year 96  
MultiFamily Non-Same-Store | Union Pointe - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 5,727  
Buildings & Improvements 69,966  
Costs capitalized subsequent to acquisition 336  
Gross amount at which carries at close of period [Abstract]    
Land 5,736  
Buildings & Improvements 70,293  
Total 76,029  
Accumulated Depreciation $ (2,723)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 76,029  
Deductions during year [Abstract]    
Balance at close of year 2,723  
MultiFamily Non-Same-Store | Venue on Knox - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 11,660  
Initial Cost to Company [Abstract]    
Land 3,438  
Buildings & Improvements 14,743  
Costs capitalized subsequent to acquisition 548  
Gross amount at which carries at close of period [Abstract]    
Land 3,530  
Buildings & Improvements 15,199  
Total 18,729  
Accumulated Depreciation $ (177)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 18,729  
Deductions during year [Abstract]    
Balance at close of year 177  
MultiFamily Non-Same-Store | Windsor - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 14,731  
Initial Cost to Company [Abstract]    
Land 2,140  
Buildings & Improvements 18,943  
Costs capitalized subsequent to acquisition 738  
Gross amount at which carries at close of period [Abstract]    
Land 2,204  
Buildings & Improvements 19,617  
Total 21,821  
Accumulated Depreciation $ (243)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 21,821  
Deductions during year [Abstract]    
Balance at close of year 243  
MultiFamily Non-Same-Store | Wingate - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 10,459  
Initial Cost to Company [Abstract]    
Land 1,480  
Buildings & Improvements 13,530  
Costs capitalized subsequent to acquisition 503  
Gross amount at which carries at close of period [Abstract]    
Land 1,526  
Buildings & Improvements 13,987  
Total 15,513  
Accumulated Depreciation $ (180)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 15,513  
Deductions during year [Abstract]    
Balance at close of year 180  
MultiFamily Non-Same-Store | Woodhaven - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 14,408  
Initial Cost to Company [Abstract]    
Land 3,940  
Buildings & Improvements 20,080  
Costs capitalized subsequent to acquisition 627  
Gross amount at which carries at close of period [Abstract]    
Land 4,040  
Buildings & Improvements 20,607  
Total 24,647  
Accumulated Depreciation $ (245)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 24,647  
Deductions during year [Abstract]    
Balance at close of year 245  
MultiFamily Non-Same-Store | Woodland Pointe - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 31,673  
Initial Cost to Company [Abstract]    
Land 5,367  
Buildings & Improvements 40,422  
Costs capitalized subsequent to acquisition 843  
Gross amount at which carries at close of period [Abstract]    
Land 5,449  
Buildings & Improvements 41,183  
Total 46,632  
Accumulated Depreciation $ (516)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 46,632  
Deductions during year [Abstract]    
Balance at close of year 516  
Total Multifamily    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 483,783  
Initial Cost to Company [Abstract]    
Land 193,982  
Buildings & Improvements 1,858,287  
Costs capitalized subsequent to acquisition 191,980  
Gross amount at which carries at close of period [Abstract]    
Land 211,363  
Buildings & Improvements 2,032,886  
Total 2,244,249  
Accumulated Depreciation (436,003)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 2,244,249  
Deductions during year [Abstract]    
Balance at close of year 436,003  
Other - Mixed Use    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 389  
Buildings & Improvements 18,920  
Costs capitalized subsequent to acquisition 5,500  
Gross amount at which carries at close of period [Abstract]    
Land 607  
Buildings & Improvements 24,202  
Total 24,809  
Accumulated Depreciation (7,201)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 24,809  
Deductions during year [Abstract]    
Balance at close of year 7,201  
Other - Mixed Use | 71 France - Edina, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 0  
Buildings & Improvements 5,879  
Costs capitalized subsequent to acquisition 867  
Gross amount at which carries at close of period [Abstract]    
Land 0  
Buildings & Improvements 6,746  
Total 6,746  
Accumulated Depreciation (1,399)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 6,746  
Deductions during year [Abstract]    
Balance at close of year 1,399  
Other - Mixed Use | Lugano at Cherry Creek - Denver, CO    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 0  
Buildings & Improvements 1,600  
Costs capitalized subsequent to acquisition 657  
Gross amount at which carries at close of period [Abstract]    
Land 0  
Buildings & Improvements 2,257  
Total 2,257  
Accumulated Depreciation $ (148)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 2,257  
Deductions during year [Abstract]    
Balance at close of year 148  
Other - Mixed Use | Oxbo - St Paul, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 0  
Buildings & Improvements 3,472  
Costs capitalized subsequent to acquisition 54  
Gross amount at which carries at close of period [Abstract]    
Land 0  
Buildings & Improvements 3,526  
Total 3,526  
Accumulated Depreciation $ (541)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 3,526  
Deductions during year [Abstract]    
Balance at close of year 541  
Other - Mixed Use | Plaza - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 389  
Buildings & Improvements 5,444  
Costs capitalized subsequent to acquisition 3,447  
Gross amount at which carries at close of period [Abstract]    
Land 607  
Buildings & Improvements 8,673  
Total 9,280  
Accumulated Depreciation (4,303)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 9,280  
Deductions during year [Abstract]    
Balance at close of year 4,303  
Other - Mixed Use | Red 20 - Minneapolis, MN    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 0  
Buildings & Improvements 2,525  
Costs capitalized subsequent to acquisition 475  
Gross amount at which carries at close of period [Abstract]    
Land 0  
Buildings & Improvements 3,000  
Total 3,000  
Accumulated Depreciation (810)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 3,000  
Deductions during year [Abstract]    
Balance at close of year $ 810  
Other - Mixed Use | Minimum | 71 France - Edina, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Other - Mixed Use | Minimum | Plaza - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Other - Mixed Use | Minimum | Red 20 - Minneapolis, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 30 years  
Other - Mixed Use | Maximum | 71 France - Edina, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Other - Mixed Use | Maximum | Plaza - Minot, ND    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Other - Mixed Use | Maximum | Red 20 - Minneapolis, MN    
Gross amount at which carries at close of period [Abstract]    
Life on which depreciation in latest income statement is computed 37 years  
Other - Commercial    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances $ 0  
Initial Cost to Company [Abstract]    
Land 246  
Buildings & Improvements 1,866  
Costs capitalized subsequent to acquisition 0  
Gross amount at which carries at close of period [Abstract]    
Land 246  
Buildings & Improvements 1,866  
Total 2,112  
Accumulated Depreciation (388)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 2,112  
Deductions during year [Abstract]    
Balance at close of year 388  
Other - Commercial | 3100 10th St SW - Minot, ND    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 0  
Initial Cost to Company [Abstract]    
Land 246  
Buildings & Improvements 1,866  
Costs capitalized subsequent to acquisition 0  
Gross amount at which carries at close of period [Abstract]    
Land 246  
Buildings & Improvements 1,866  
Total 2,112  
Accumulated Depreciation $ (388)  
Life on which depreciation in latest income statement is computed 30 years  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year $ 2,112  
Deductions during year [Abstract]    
Balance at close of year 388  
Total    
Real Estate And Accumulated Depreciation [Abstract]    
Encumbrances 483,783  
Initial Cost to Company [Abstract]    
Land 194,617  
Buildings & Improvements 1,879,073  
Costs capitalized subsequent to acquisition 197,480  
Gross amount at which carries at close of period [Abstract]    
Land 212,216  
Buildings & Improvements 2,058,954  
Total 2,271,170  
Accumulated Depreciation (443,592)  
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]    
Balance at close of year 2,271,170  
Deductions during year [Abstract]    
Balance at close of year $ 443,592