Segment Disclosures - Revenues and Assets by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Disclosure
Total revenues	$ 436,154	$ 479,197
Operating segment
Segment Disclosure
Total revenues	436,154	479,197
Operating segment | Senior housing triple-net
Segment Disclosure
Total revenues	58,892	74,289
Operating segment | SHOP
Segment Disclosure
Total revenues	126,181	144,670
Operating segment | Life science
Segment Disclosure
Total revenues	94,473	99,622
Operating segment | Medical office
Segment Disclosure
Total revenues	142,195	133,220
Operating segment | Other non-reportable segments
Segment Disclosure
Total revenues	$ 14,413	$ 27,396