Segment Disclosures - Revenues and Assets by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Disclosure
Total revenues	$ 469,551	$ 458,928	$ 948,748	$ 951,096
Operating segment
Segment Disclosure
Total revenues	469,551	458,928	948,748	951,096
Operating segment | Senior housing triple-net
Segment Disclosure
Total revenues	70,713	78,079	145,003	178,112
Operating segment | SHOP
Segment Disclosure
Total revenues	138,352	125,416	283,022	265,644
Operating segment | Life science
Segment Disclosure
Total revenues	101,031	86,730	200,653	172,050
Operating segment | Medical office
Segment Disclosure
Total revenues	125,246	119,164	249,180	237,535
Operating segment | Other non-reportable segments
Segment Disclosure
Total revenues	$ 34,209	$ 49,539	$ 70,890	$ 97,755