Acquisitions, Dispositions and Other Transactions - Healthpeak CCRC Venture and Master Lease Transactions (Details) $ in Thousands		3 Months Ended
	Oct. 01, 2019 USD ($) community entry_fee extension_option	Mar. 31, 2020 USD ($) community entry_fee	Mar. 31, 2019 USD ($)
Business Acquisition [Line Items]
Number of additional entry fee | entry_fee	1
Gain (loss) on sale of assets, net		$ 372,839	$ (702)
Payments (proceeds) for management agreement termination fee		100,000
Gain (loss) on extinguishment of debt		$ 19,181	$ (67)
Number of communities previously subject to sale leaseback transactions | community		8
CCRC Ventures, LLC
Business Acquisition [Line Items]
Gain (loss) on sale of assets, net		$ 93,100
CCRC Ventures, LLC | CCRCs
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	51.00%
Number of entry fee | entry_fee	14
Purchase price	$ 295,200
Payments to acquire interest in joint venture	1,060,000
Gain (loss) on sale of assets, net		$ 370,700
Number of entry fee, sales | entry_fee		2
HCP, Inc. | CCRCs
Business Acquisition [Line Items]
Payments (proceeds) for management agreement termination fee	$ 100,000
Master Lease Transactions
Business Acquisition [Line Items]
Number of continuing communities | community	24
Operating leases, rent expense	$ 41,700
Operating leases, rent expense, annual escalator rate	2.40%
Operating lease, initial lease rate	7.00%
Gain (loss) on extinguishment of debt		$ 19,700
Financing lease obligations, carrying value		$ 105,100
Master Lease Transactions | HCP, Inc.
Business Acquisition [Line Items]
Payments to acquire interest in joint venture	$ 405,500
Number of communities leased | community	25
Number of communities, acquired, previously leased or managed | community	18
Number of leases communities transferred to successor operator | community	1
Number of continuing communities | community	24
Lessee, operating lease, number of extensions | extension_option	2
Lessee, operating lease, number of extensions, term	10 years
Operating lease, capital expenditures, availability	$ 35,000
Non-Recourse First Mortgages | Master Lease Transactions
Business Acquisition [Line Items]
Proceeds from issuance of debt	$ 192,600