Fair Value Measurements - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 01, 2021 USD ($)	Jul. 26, 2020 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) lease community	Dec. 31, 2020 USD ($) community	Dec. 31, 2019 USD ($)	Sep. 30, 2020 USD ($) community	Jun. 30, 2020 USD ($) community	Mar. 31, 2020 USD ($) community	Jan. 01, 2019 USD ($) community	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities			$ 182,393	$ 172,905
investment in unconsolidated ventures			67,424	4,898
Debt			$ 3,841,212	3,915,988
Number of communities leased | lease			233
Cumulative effect of change in accounting principle			$ 699,623	802,729	$ 698,725					$ 1,018,413
Health Care Services | Securities Purchase Agreement | HCA Healthcare, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
investment in unconsolidated ventures	$ 100,000
Percentage of ownership after transaction	20.00%		20.00%
Purchase price	$ 400,000
Accumulated Deficit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative effect of change in accounting principle			$ (3,410,474)	(3,311,184)	(3,393,088)					(3,069,272)
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative effect of change in accounting principle				$ 0	(115)					$ (55,885)
Condensed Consolidated Balance Sheet
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of communities leased | community			11	5		2	9	35	25
Estimated fair value			$ 31,000	$ 2,300		$ 3,000	$ 10,300	$ 106,700	$ 56,600
Ventas, Inc | The Warrant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of shares authorized to be purchased | shares		16,300,000
Share price (in usd per share) | $ / shares		$ 3.00
Issuance of warrants		$ 22,900
Volatility rate		65.00%
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt			3,800,000	3,900,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities			182,400
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Operating lease right-of-use assets			16,600	76,300	10,200
Property, plant and equipment impairment			$ 6,400	$ 29,300	$ 27,200
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate			9.00%
Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalization rate			7.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate			12.30%
Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalization rate			9.00%
ASU 2016-02
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
investment in unconsolidated ventures									(2,000)
Cumulative effect of change in accounting principle									(56,000)
ASU 2016-02 | Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cumulative effect of change in accounting principle									$ 58,100