Subsequent Events (Details) $ in Millions		1 Months Ended		3 Months Ended		12 Months Ended
	May 01, 2020 USD ($)	Apr. 30, 2020 USD ($) property	Jan. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) property	Mar. 31, 2019 USD ($) property	Dec. 31, 2019 USD ($) property
Medical office
Subsequent Event [Line Items]
Number of assets to be sold | property						10
Life science
Subsequent Event [Line Items]
Number of assets to be sold | property					1	1
SHOP
Subsequent Event [Line Items]
Number of assets to be sold | property				7	9	18
SHOP | Subsequent Event
Subsequent Event [Line Items]
Number of assets to be sold | property		1
Massachusetts | Life science
Subsequent Event [Line Items]
Deposit, nonrefundable			$ 20
Massachusetts | Life science | Subsequent Event
Subsequent Event [Line Items]
Payments to acquire real estate		$ 320
San Diego | Medical office | Subsequent Event
Subsequent Event [Line Items]
Number of assets to be sold | property		3
Proceeds from nonrefundable deposit	$ 5
Medical office
Subsequent Event [Line Items]
Proceeds from sale of buildings						$ 23
Medical office | San Diego | Subsequent Event
Subsequent Event [Line Items]
Proceeds from sale of buildings		$ 106
SHOP
Subsequent Event [Line Items]
Proceeds from sale of buildings				$ 36	$ 68	$ 181
SHOP | Subsequent Event
Subsequent Event [Line Items]
Proceeds from sale of buildings		$ 12