Segment Disclosures - Revenues and Assets by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Disclosure
Total revenues	$ 458,928	$ 538,335	$ 951,096	$ 1,058,792
Operating segment
Segment Disclosure
Total revenues	458,928	538,335	951,096	1,058,792
Operating segment | Senior housing triple-net
Segment Disclosure
Total revenues	78,079	108,841	178,112	215,731
Operating segment | SHOP
Segment Disclosure
Total revenues	125,416	164,202	265,644	329,964
Operating segment | Life science
Segment Disclosure
Total revenues	86,730	90,201	172,050	179,149
Operating segment | Medical office
Segment Disclosure
Total revenues	119,164	110,205	237,535	218,228
Operating segment | Other non-reportable segments
Segment Disclosure
Total revenues	$ 49,539	$ 64,886	$ 97,755	$ 115,720