Variable Interest Entities - Narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) joint_venture property investment tenant loan facility	Mar. 31, 2020 property	Dec. 31, 2020 asset
Variable Interest Entity [Line Items]
Number of investments in senior housing development joint ventures | investment	2
Number of properties disposed | property		18
Term of facility	1 month	1 month
Exchange accommodation titleholder, real estate, carrying value | $	$ 417
VIE tenant - operating leases
Variable Interest Entity [Line Items]
Number of properties leased (in properties) | property	2
Number of VIE tenants (in tenants) | tenant	1
Unconsolidated Variable Interest Entities
Variable Interest Entity [Line Items]
Number of unconsolidated joint ventures (in joint ventures) | joint_venture	4
Number of VIE borrowers with marketable debt securities (in joint ventures) | joint_venture	1
Number of loans to VIE borrowers (in loans) | loan	1
CCRC OpCo
Variable Interest Entity [Line Items]
Ownership percentage (as a percent)	49.00%
Hcp Ventures V
Variable Interest Entity [Line Items]
Ownership percentage (as a percent)	51.00%
Life science joint ventures
Variable Interest Entity [Line Items]
Ownership percentage (as a percent)	99.00%
MSREI JV
Variable Interest Entity [Line Items]
Ownership percentage (as a percent)	51.00%
Consolidated Lessees VIE
Variable Interest Entity [Line Items]
Number of properties leased (in properties) | property	4
DownREIT Partnerships
Variable Interest Entity [Line Items]
Number of controlling ownership interest entities as a managing member | joint_venture	7
Senior Housing Triple-Net | Loan - seller financing
Variable Interest Entity [Line Items]
Number of properties disposed | facility	7
Term of facility	5 years
Life science
Variable Interest Entity [Line Items]
Number of properties acquired | asset			1