Segment Disclosures - Summary Information for the Reportable Segments (Details) $ in Thousands	1 Months Ended			3 Months Ended
	Jan. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Mar. 31, 2018 USD ($) facility	Mar. 31, 2017 USD ($) facility
Segment Disclosure
Number of SH NNN facilities transitioned to RIDEA structure | facility				0
Segment reporting information, revenues
Rental revenues				$ 472,832	$ 473,837
Operating expenses				(172,552)	(159,081)
Segment NOI				300,280	314,756
Adjustments to NOI				(9,686)	(4,427)
Adjusted NOI				290,594	310,329
Addback adjustments				9,686	4,427
Interest income				6,365	18,331
Interest expense				(75,102)	(86,718)
Depreciation and amortization				(143,250)	(136,554)
General and administrative				(29,175)	(22,478)
Transaction costs				(2,195)	(1,057)
Gain (loss) on sales of real estate, net				20,815	317,258
Other income (expense), net				(40,407)	51,208
Income tax benefit (expense)				5,336	6,162
Equity income (loss) from unconsolidated JVs				570	3,269
Net income (loss)				43,237	464,177
Corporate and other assets
Segment reporting information, revenues
Rental revenues				0	0
Operating expenses				0	0
Segment NOI				0	0
Adjustments to NOI				0	0
Adjusted NOI				0	0
Addback adjustments				0	0
Interest income				0	0
Interest expense				(72,583)	(79,265)
Depreciation and amortization				0	0
General and administrative				(29,175)	(22,478)
Transaction costs				(2,195)	(1,057)
Gain (loss) on sales of real estate, net				0	0
Other income (expense), net				160	313
Income tax benefit (expense)				5,336	6,162
Equity income (loss) from unconsolidated JVs				0	0
Net income (loss)				(98,457)	$ (96,325)
Senior housing triple-net
Segment Disclosure
Number of SH NNN facilities transitioned to RIDEA structure | facility					1
Segment reporting information, revenues
Gain (loss) on sales of real estate, net		$ 170,000
Senior housing triple-net | Operating segment
Segment reporting information, revenues
Rental revenues				74,289	$ 100,034
Operating expenses				(1,045)	(1,111)
Segment NOI				73,244	98,923
Adjustments to NOI				(1,865)	(1,839)
Adjusted NOI				71,379	97,084
Addback adjustments				1,865	1,839
Interest income				0	0
Interest expense				(600)	(627)
Depreciation and amortization				(21,906)	(26,411)
General and administrative				0	0
Transaction costs				0	0
Gain (loss) on sales of real estate, net				0	268,464
Other income (expense), net				0	0
Income tax benefit (expense)				0	0
Equity income (loss) from unconsolidated JVs				0	0
Net income (loss)				50,738	340,349
SHOP
Segment reporting information, revenues
Gain (loss) on sales of real estate, net	$ 21,000
SHOP | Operating segment
Segment reporting information, revenues
Rental revenues				144,670	140,228
Operating expenses				(101,746)	(94,539)
Segment NOI				42,924	45,689
Adjustments to NOI				(1,607)	(310)
Adjusted NOI				41,317	45,379
Addback adjustments				1,607	310
Interest income				0	0
Interest expense				(988)	(4,596)
Depreciation and amortization				(27,628)	(26,358)
General and administrative				0	0
Transaction costs				0	0
Gain (loss) on sales of real estate, net				20,815	366
Other income (expense), net				0	0
Income tax benefit (expense)				0	0
Equity income (loss) from unconsolidated JVs				0	0
Net income (loss)				35,123	15,101
Life science
Segment reporting information, revenues
Gain (loss) on sales of real estate, net			$ 45,000
Life science | Operating segment
Segment reporting information, revenues
Rental revenues				99,622	85,321
Operating expenses				(21,809)	(17,319)
Segment NOI				77,813	68,002
Adjustments to NOI				(3,751)	(305)
Adjusted NOI				74,062	67,697
Addback adjustments				3,751	305
Interest income				0	0
Interest expense				(83)	(104)
Depreciation and amortization				(36,080)	(33,791)
General and administrative				0	0
Transaction costs				0	0
Gain (loss) on sales of real estate, net				0	44,633
Other income (expense), net				0	0
Income tax benefit (expense)				0	0
Equity income (loss) from unconsolidated JVs				0	0
Net income (loss)				41,650	78,740
Medical office | Operating segment
Segment reporting information, revenues
Rental revenues				123,935	118,371
Operating expenses				(46,696)	(44,864)
Segment NOI				77,239	73,507
Adjustments to NOI				(1,071)	(961)
Adjusted NOI				76,168	72,546
Addback adjustments				1,071	961
Interest income				0	0
Interest expense				(120)	(129)
Depreciation and amortization				(45,519)	(42,729)
General and administrative				0	0
Transaction costs				0	0
Gain (loss) on sales of real estate, net				0	0
Other income (expense), net				0	0
Income tax benefit (expense)				0	0
Equity income (loss) from unconsolidated JVs				0	0
Net income (loss)				31,600	30,649
Other non-reportable segments | Operating segment
Segment reporting information, revenues
Rental revenues				30,316	29,883
Operating expenses				(1,256)	(1,248)
Segment NOI				29,060	28,635
Adjustments to NOI				(1,392)	(1,012)
Adjusted NOI				27,668	27,623
Addback adjustments				1,392	1,012
Interest income				6,365	18,331
Interest expense				(728)	(1,997)
Depreciation and amortization				(12,117)	(7,265)
General and administrative				0	0
Transaction costs				0	0
Gain (loss) on sales of real estate, net				0	3,795
Other income (expense), net				(40,567)	50,895
Income tax benefit (expense)				0	0
Equity income (loss) from unconsolidated JVs				570	3,269
Net income (loss)				$ (17,417)	$ 95,663