Acquisitions, Dispositions and Other Transactions - Healthpeak CCRC Venture and Master Lease Transactions (Details)		3 Months Ended			9 Months Ended
	Oct. 01, 2019 USD ($) community extension_option entry_fee	Sep. 30, 2020 USD ($) community	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Business Acquisition [Line Items]
Number of additional entry fee | entry_fee	1
Purchase price		$ 25,000,000.0
Gain on sale of assets		2,209,000		$ 579,000	$ 374,019,000	$ 2,723,000
Payments (proceeds) for management agreement termination fee			$ 100,000,000.0
Gain (loss) on extinguishment of debt		$ (7,917,000)		$ (2,455,000)	11,107,000	$ (5,194,000)
Number of communities previously subject to sale leaseback transactions | community		8
HCP, Inc. | CCRCs
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	51.00%
Number of entry fee | entry_fee	14
Purchase price	$ 289,200,000
Working capital adjustment		$ 5,900,000
Payments to acquire interest in joint venture	1,060,000,000.00
Gain on sale of assets					$ 369,800,000
Payments (proceeds) for management agreement termination fee	$ 100,000,000.0
Master Lease Transactions
Business Acquisition [Line Items]
Number of continuing communities | community	24
Initial annual base rent	$ 41,700,000
Annual escalator rate	2.40%
Operating lease, initial lease rate	7.00%
Gain (loss) on extinguishment of debt		19,700,000
Financing lease obligations, carrying value		$ 105,100,000
Master Lease Transactions | HCP, Inc.
Business Acquisition [Line Items]
Payments to acquire interest in joint venture	$ 405,500,000
Number of communities leased | community	25
Number of communities, acquired, previously leased or managed | community	18
Direct acquisition costs	$ 1,700,000
Number of leases communities transferred to successor operator | community	1
Number of continuing communities | community	24
Number of extensions | extension_option	2
Term of extensions	10 years
Operating lease, capital expenditures, availability	$ 35,000,000.0
Non-Recourse First Mortgages | Master Lease Transactions
Business Acquisition [Line Items]
Proceeds from issuance of debt	$ 192,600,000