Segment Disclosures - Revenues and Assets by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Disclosure
Total revenues	$ 539,950	$ 530,555	$ 538,332	$ 520,457	$ 520,325	$ 508,900	$ 459,806	$ 451,458	$ 2,129,294	$ 1,940,489	$ 1,636,833
Assets held for sale and discontinued operations, net	927,866				5,654,326				927,866	5,654,326
Total assets	15,759,265				21,449,849				15,759,265	21,449,849
Goodwill	42,386				47,019				42,386	47,019
Impairment related to goodwill	0
Operating segment
Segment Disclosure
Gross assets	15,263,090				15,407,019				15,263,090	15,407,019
Accumulated depreciation and amortization	(2,900,060)				(2,704,425)				(2,900,060)	(2,704,425)
Total assets	12,363,030				12,702,594				12,363,030	12,702,594
Operating segment | SH NNN
Segment Disclosure
Total revenues									423,118	428,269	538,113
Gross assets	3,871,720				5,092,443				3,871,720	5,092,443
Goodwill	16,000				21,000				16,000	21,000
Operating segment | SHOP
Segment Disclosure
Total revenues									686,822	518,264	243,612
Gross assets	3,623,931				3,195,384				3,623,931	3,195,384
Goodwill	9,000				9,000				9,000	9,000
Operating segment | Life science
Segment Disclosure
Total revenues									358,537	342,984	314,114
Gross assets	4,029,500				3,682,308				4,029,500	3,682,308
Operating segment | Medical office
Segment Disclosure
Total revenues									446,280	415,351	368,055
Gross assets	3,737,939				3,436,884				3,737,939	3,436,884
Goodwill	11,000				11,000				11,000	11,000
Operating segment | Other
Segment Disclosure
Total revenues									214,537	235,621	$ 172,939
Total assets	1,685,563				1,787,579				1,685,563	1,787,579
Goodwill	6,000				6,000				6,000	6,000
Other non-segment
Segment Disclosure
Total assets	$ 782,806				$ 1,305,350				$ 782,806	$ 1,305,350