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Real Estate Investments - Narrative (Details) $ in Thousands |  | 1 Months Ended | 12 Months Ended |  |  |
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Dec. 23, 2021 | Jan. 31, 2022 USD ($) property | Dec. 31, 2021 USD ($) ft² building property community unit | Jan. 31, 2020 USD ($) | May 31, 2019 USD ($) unit building | Dec. 31, 2021 USD ($) ft² property building community unit | Dec. 31, 2020 USD ($) ft² property building | Dec. 31, 2019 USD ($) ft² unit building property | Jun. 09, 2021 unit community | Sep. 30, 2019 property | Mar. 31, 2017
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate investment properties, net |  |  | $ 5,075,749 |  |  | $ 5,075,749 | $ 5,715,829 |  |  |  |
Real estate property - accumulated depreciation |  |  | $ 1,737,807 |  |  | $ 1,737,807 | 1,694,901 |  |  |  |
Number of properties owned (property) | property |  |  | 390 |  |  | 390 |  |  |  |  |
Total assets |  |  | $ 6,623,514 |  |  | $ 6,623,514 | 6,476,424 | $ 6,653,826 |  |  |
Secured debt and finance leases, net |  |  | 69,713 |  |  | 69,713 | 691,573 |  |  |  |
Proceeds from sale of interest in joint venture, net |  |  |  |  |  | 367,033 | 0 | 0 |  |  |
Gain on sale of properties |  |  |  |  |  | 492,272 | 6,487 | 39,696 |  |  |
Equity method investments, carrying value |  |  | 31,540 |  |  | 31,540 | 73,772 |  |  |  |
Impairment of assets |  |  |  |  |  | (174) | 106,972 | $ 115,201 |  |  |
Lease committed but unspent tenant related obligations |  |  |  |  |  | 76,573 | 19,159 |  |  |  |
Variable Interest Entity, Primary Beneficiary |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Total assets |  |  |  |  |  |  | 970,142 |  |  |  |
Secured debt and finance leases, net |  |  |  |  |  |  | 697,129 |  |  |  |
Seaport Innovation LLC |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Aggregate property valuation amount |  |  | 1,700,000 |  |  | 1,700,000 |  |  |  |  |
Aggregate principal amount of mortgage debt |  |  | 620,000 |  |  | 620,000 |  |  |  |  |
Land |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate investment properties, net |  |  | 741,501 |  |  | 741,501 | 789,125 |  |  |  |
Buildings and Improvements |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate investment properties, net |  |  | 6,072,055 |  |  | 6,072,055 | 6,621,605 |  |  |  |
Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate property - accumulated depreciation |  |  | 1,587,573 |  |  | 1,587,573 | 1,561,751 |  |  |  |
Building Improvements |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate property - accumulated depreciation |  |  | $ 150,234 |  |  | $ 150,234 | $ 133,150 |  |  |  |
Medical Office Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 7 | 20 |  |  |
Impairment of assets |  |  |  |  |  |  | $ 8,558 | $ 43,035 |  |  |
Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 28 | 25 |  |  |
Number of units in real estate property | unit |  |  | 27,672 |  |  | 27,672 |  |  |  |  |
Gain on sale of properties |  |  |  |  |  |  | $ 225 |  |  |  |
Impairment of assets |  |  |  |  |  |  | $ 98,414 | $ 72,166 |  |  |
Welness Centers |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 10 |  |  | 10 |  |  |  |  |
Area of real estate properties (in square feet) | ft² |  |  | 812,000 |  |  | 812,000 |  |  |  |  |
SNF |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Gain on sale of properties |  |  |  |  |  | $ 200 |  |  |  |  |
Life Science |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  |  | 1 |  |  |
Medical Office Building and Life Science Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 116 |  |  | 116 |  |  |  |  |
Area of real estate properties (in square feet) | ft² |  |  | 9,800,000 |  |  | 9,800,000 |  |  |  |  |
Medical Office Building and Life Science Building | Capital Commitments |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties (in square feet) | ft² |  |  | 2,600,000 |  |  | 2,600,000 | 1,000,000 |  |  |  |
Leases committed expenditure |  |  |  |  |  | $ 97,520 | $ 17,901 |  |  |  |
Medical Office Building and Life Science Building | Subsequent Event | Unrelated Investor One |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Equity method investments, carrying value |  | $ 100,800 |  |  |  |  |  |  |  |  |
Medical Office Building and Life Science Building | Subsequent Event | Unrelated Investor Two |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Equity method investments, carrying value |  | 95,900 |  |  |  |  |  |  |  |  |
Senior Living Communities, Independent Living, Assisted Living, and Skilled Nursing Facility |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 264 |  |  | 264 |  |  |  |  |
Land Parcel | Arizona |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Real estate purchase price |  |  |  | $ 2,600 |  |  |  |  |  |  |
Joint Venture |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Gain on sale of properties |  |  | $ 461,434 |  |  |  |  |  |  |  |
Joint Venture | Seaport Innovation LLC |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 1 |  |  | 1 |  |  |  |  |
Area of real estate properties (in square feet) | ft² |  |  | 1,134,479 |  |  | 1,134,479 |  |  |  |  |
Number of properties included in joint venture agreement | property |  |  |  |  |  | 1 |  |  |  |  |
Equity method investment ownership percentage | 20.00% |  | 20.00% |  |  | 20.00% |  |  |  |  | 55.00%
Additional equity joint venture percentage | 35.00% |  | 35.00% |  |  |  |  |  |  |  |
Proceeds from sale of interest in joint venture, net |  |  | $ 373,847 |  |  |  |  |  |  |  |
Joint Venture | Investor | Seaport Innovation LLC |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Equity method investment ownership percentage |  |  |  |  |  |  |  |  |  |  | 45.00%
Joint Venture | Subsequent Event |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Aggregate property valuation amount |  | 702,500 |  |  |  |  |  |  |  |  |
Aggregate principal amount of mortgage debt |  | $ 456,600 |  |  |  |  |  |  |  |  |
Joint Venture | Medical Office Building and Life Science Building | Subsequent Event |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties included in joint venture agreement | property |  | 10 |  |  |  |  |  |  |  |  |
Equity method investment ownership percentage |  | 20.00% |  |  |  |  |  |  |  |  |
Proceeds from sale of interest in joint venture, net |  | $ 653,300 |  |  |  |  |  |  |  |  |
Joint Venture | Medical Office Building and Life Science Building | Subsequent Event | Unrelated Investor One |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Equity method investment ownership percentage |  | 41.00% |  |  |  |  |  |  |  |  |
Joint Venture | Medical Office Building and Life Science Building | Subsequent Event | Unrelated Investor Two |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Equity method investment ownership percentage |  | 39.00% |  |  |  |  |  |  |  |  |
Five Star | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | community |  |  |  |  |  |  |  |  | 120 |  |
Five Star | Five Star |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Amount of improvements to communities |  |  |  |  |  |  |  | $ 111,603 |  |  |
Payments to acquire property, plant, and equipment |  |  |  |  |  |  |  | $ 49,155 |  |  |
Scenario, Adjustment | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 10 |  |  | 10 |  |  |  |  |
Impairment of assets |  |  |  |  |  | $ (174) |  |  |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Medical Office Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 1 | 15 |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 10 | 2 |  |  |
Number of units in real estate property | property |  |  |  |  |  |  | 820 |  |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Medical Office Building and Life Science Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties (in square feet) | ft² |  |  |  |  |  |  | 355,656 |  |  |  |
Number of units in real estate property | property |  |  |  |  |  |  | 5 |  |  |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Five Star | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | community |  |  | 108 |  |  | 108 |  |  | 108 |  |
Number of units in real estate property | unit |  |  |  |  |  |  |  |  | 1,500 |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Scenario, Adjustment | Five Star | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of units in real estate property | unit |  |  |  |  |  |  |  |  | 7,500 |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | building |  |  | 5 |  |  | 5 | 27 | 46 |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  | $ 104,500 | $ 152,893 | $ 260,783 |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Medical Office Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 4 |  |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 9 |  |  |  |
Number of real estate properties closed | property |  |  |  |  |  |  | 7 |  |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | SNF |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  | 8 |  |  | 8 |  |  |  |  |
Number of units in real estate property | property |  |  |  |  |  |  |  |  |  | 15 |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | SNF | California |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | building |  |  |  |  | 3 |  |  |  |  |  |
Number of units in real estate property | unit |  |  |  |  | 278 |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  | $ 21,500 |  |  |  |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Medical Office Building and Life Science Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  |  | 5 |  |  |
Discontinued Operations, Held-for-sale | Senior Living Communities |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  |  | 12 |  |  |
Number of units in real estate property | unit |  |  |  |  |  |  |  | 1,670 |  |  |
Discontinued Operations, Held-for-sale | Medical Office Building and Life Science Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  |  | 21 |  |  |
Area of real estate properties (in square feet) | ft² |  |  |  |  |  |  |  | 875,617 |  |  |
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Medical Office Building |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |
Number of properties owned (property) | property |  |  |  |  |  |  | 10 |  |  |  |

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