Segment Disclosures - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) facility	Dec. 31, 2017 USD ($) facility	Dec. 31, 2016 USD ($) facility
Segment Reporting Information [Line Items]
Impairment related to goodwill		$ 0	$ 0
Goodwill	$ 47,000,000	$ 47,000,000
Senior housing triple-net
Segment Reporting Information [Line Items]
Number of SH NNN facilities transitioned to RIDEA structure (in facilities) | facility	22	25	17
Operating segment | Senior housing triple-net
Segment Reporting Information [Line Items]
Goodwill	$ 21,000,000	$ 21,000,000
Operating segment | SHOP
Segment Reporting Information [Line Items]
Goodwill	9,000,000	9,000,000
Operating segment | Medical office
Segment Reporting Information [Line Items]
Goodwill	11,000,000	11,000,000
Operating segment | Other non-reportable segments
Segment Reporting Information [Line Items]
Goodwill	$ 6,000,000	$ 6,000,000