Summary of Significant Accounting Policies - Narrative (Details)			12 Months Ended
	Jan. 31, 2020 USD ($) facility property	Jan. 01, 2018 USD ($)	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($) facility		Dec. 31, 2018 USD ($)		Mar. 31, 2020 property	Jan. 01, 2020 USD ($)	Oct. 31, 2019 property	Jan. 01, 2019 USD ($)	Dec. 31, 2017 USD ($)		Jan. 31, 2017
Schedule of Equity Method Investments [Line Items]
Residency agreement term, minimum			30 days
Residency agreement term, maximum			1 year
Maximum period available for occupancy from cessation of significant construction activity			1 year
Maximum useful life of building and improvements			60 years
Advertising expense			$ 18,000,000	$ 13,000,000		$ 9,000,000
Property count | property	15
HCP’s capital			6,788,345,000	6,085,058,000
Cumulative effect of new accounting principle			7,344,572,000	6,667,474,000		6,512,591,000						$ 5,594,938,000
Present value of lease liability			179,895,000	152,400,000
Right-of-use asset, net			192,349,000	167,316,000
Intangible assets, net			519,917,000	$ 260,204,000
Other Non-Reporting Segment
Schedule of Equity Method Investments [Line Items]
Number of deconsolidating assets | facility				19
Assets leased to others | Other Non-Reporting Segment
Schedule of Equity Method Investments [Line Items]
Property count | property								1
CCRC JV Investment | CCRC
Schedule of Equity Method Investments [Line Items]
Property count | facility	15
CCRC JV Investment | Assets leased to others | Other Non-Reporting Segment
Schedule of Equity Method Investments [Line Items]
Property count | property								15		15
Brookedale MTCA | Assets leased to others | Other Non-Reporting Segment
Schedule of Equity Method Investments [Line Items]
Property count | property	13
Brookedale MTCA | CCRC JV Investment
Schedule of Equity Method Investments [Line Items]
Non refundable entrance fee liabilities	$ 436,000,000		$ 484,000,000	$ 68,000,000
Property count | property	15
Equity method investments	$ 323,000,000
Brookedale MTCA | CCRC JV Investment | CCRC
Schedule of Equity Method Investments [Line Items]
Property count | facility	13
Brookedale MTCA | CCRC JV Investment | Assets leased to others | Other Non-Reporting Segment
Schedule of Equity Method Investments [Line Items]
Property count | property	13		13					13
Discontinued Operations
Schedule of Equity Method Investments [Line Items]
Advertising expense			$ 12,000,000	13,000,000		9,000,000
RIDEA II
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage														40.00%
Equity method investments		$ 121,000,000
ASU 2016-02
Schedule of Equity Method Investments [Line Items]
Present value of lease liability											$ 153,000,000
Right-of-use asset, net											166,000,000
Accrued Rent											20,000,000
Intangible assets, net											33,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09
Schedule of Equity Method Investments [Line Items]
HCP’s capital		79,000,000
Cumulative effect of change on beginning retained earnings		30,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09 | RIDEA II
Schedule of Equity Method Investments [Line Items]
Fair value of equity investment		$ 107,000,000
Cumulative Dividends In Excess Of Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle			$ (3,976,232,000)	(3,601,199,000)		(2,927,196,000)						(3,370,520,000)
Cumulative Effect, Period of Adoption, Adjustment
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				(1,524,000)	[1]	590,000	[2]		$ 2			79,144,000	[3]
Cumulative Effect, Period of Adoption, Adjustment | Cumulative Dividends In Excess Of Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle				$ (1,524,000)	[1]	$ 590,000	[2]					$ 79,144,000	[3]
Cumulative Effect, Period of Adoption, Adjustment | Cumulative Dividends In Excess Of Earnings | ASU 2016-02
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle											$ 1,000,000

[1] On January 1, 2020, the Company adopted a series of ASUs related to accounting for credit losses and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.

[2] On January 1, 2019, the Company adopted a series of ASUs related to accounting for leases, and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.

[3] On January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) No. 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (“ASU 2017-05”), and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.