Impairments of Real Estate (Details)	3 Months Ended			12 Months Ended
	Mar. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($) property	Oct. 31, 2019 property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of real estate				$ 0
Net real estate				13,023,483,000	$ 12,667,429,000
Impairments and loan loss reserves (recoveries), net				7,004,000	55,896,000	$ 244,253,000
Goodwill, impairment loss				0	0	0
Goodwill				18,000,000	18,000,000
Insured event loss				(7,168,000)	(1,632,000)	(469,000)
Planned MOB Demolition, Tenant Relocation And Other Costs
Impaired Long-Lived Assets Held and Used [Line Items]
Expense on other	$ 14,000,000
Casualty-Related Losses
Impaired Long-Lived Assets Held and Used [Line Items]
Insured event loss				$ 6,000,000	5,000,000	500,000
Minimum
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment calculation price range						$ 13,000
Terminal capitalization rate						5.50%
Discount rates						8.00%
Maximum
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment calculation price range						$ 300,000
Terminal capitalization rate						7.50%
Discount rates						9.50%
Weighted Average
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment calculation price range						$ 164,000
Held-for-sale
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill, impairment loss		$ 22,000,000	$ 7,000,000		29,000,000
Goodwill					0
Discontinued Operations
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments and loan loss reserves (recoveries), net						201,000,000
Shop Assets, Senior Housing Triple-net Assets, MOBs, and Other Non-Reportable Asset
Impaired Long-Lived Assets Held and Used [Line Items]
Aggregate carrying value before impairment						960,000,000
Real estate held-for-sale						$ 750,000,000
Medical Office
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of real estate					$ 22,000,000
Number of real estate properties impaired | property					3	5
Property count | property					4
Medical Office | Held-for-use
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired | property					1
Medical Office | Held-for-sale
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired | property					3
Medical Office | Impairments 2021 | Held-for-use
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of real estate					$ 17,000,000
Medical Office | Impairments 2021 | Held-for-sale
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of real estate					5,000,000
Net real estate					14,000,000
Senior Housing Operating Portfolio
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of real estate					$ 4,000,000
Number of real estate properties impaired | property					1	42
Senior Housing Operating Portfolio | Impairments 2021
Impaired Long-Lived Assets Held and Used [Line Items]
Aggregate carrying value before impairment					$ 20,000,000
Real estate held-for-sale					$ 16,000,000
Life Science
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments and loan loss reserves (recoveries), net						$ 15,000,000
Number of properties intended to be demolished | property						1
Senior Housing Triple Net, SHOP, and MOB
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments and loan loss reserves (recoveries), net						$ 210,000,000
Senior Housing Triple Net
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired | property						5
Property count | property							43
MOB Land Parcels
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired | property						1