Segment Disclosures - Assets by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Segment Disclosure
Total assets	$ 21,449,849	$ 21,331,436
Goodwill	50,346	50,346
Impairment related to goodwill	0
Operating segment
Segment Disclosure
Gross assets	23,334,330	23,042,397
Accumulated depreciation and amortization	(3,005,270)	(2,600,072)
Total assets	20,329,060	20,442,325
Operating segment | Senior housing
Segment Disclosure
Gross assets	9,812,142	8,383,345
Goodwill	31,000	31,000
Operating segment | Post-acute/skilled
Segment Disclosure
Gross assets	5,162,947	6,875,122
Goodwill	3,000	3,000
Operating segment | Life science
Segment Disclosure
Gross assets	4,267,373	4,154,789
Operating segment | Medical office
Segment Disclosure
Gross assets	3,469,048	2,988,888
Goodwill	11,000	11,000
Operating segment | Hospital
Segment Disclosure
Gross assets	622,820	640,253
Goodwill	5,000	5,000
Other non-segment
Segment Disclosure
Total assets	$ 1,120,789	$ 889,111