Segment Disclosures - Summary Information for the Reportable Segments (Details) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019 USD ($) facility	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($) facility	Sep. 30, 2018 USD ($) facility	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) facility	Sep. 30, 2018 USD ($) facility
Segment reporting information, revenues
Rental revenues	$ 535,230			$ 454,786			$ 1,458,824	$ 1,395,722
Operating expenses	(248,069)			(181,207)			(630,989)	(527,625)
Segment NOI	287,161			273,579			827,835	868,097
Adjustments to NOI	(8,963)			(703)			(14,252)	(14,051)
Adjusted NOI	278,198			272,876			813,583	854,046
Addback adjustments	8,963			703			14,252	14,051
Interest income	2,741			1,236			6,868	9,048
Interest expense	(61,230)			(63,486)			(167,499)	(211,626)
Depreciation and amortization	(171,944)			(132,198)			(469,191)	(418,740)
General and administrative	(22,970)			(23,503)			(71,445)	(75,192)
Transaction costs	(1,319)			(4,489)			(7,174)	(9,088)
Recoveries (impairments), net	(38,257)			(5,268)			(115,653)	(19,180)
Gain (loss) on sales of real estate, net	(784)	$ 11,000	$ 8,000	95,332			18,708	162,211
Loss on debt extinguishments	(35,017)			(43,899)			(36,152)	(43,899)
Other income (expense), net	693			1,604			24,834	(37,017)
Income tax benefit (expense)	6,261			4,929			11,583	14,919
Equity income (loss) from unconsolidated joint ventures	(7,643)			(911)			(10,012)	(442)
Net income (loss)	(42,308)			102,926			12,702	239,091
Corporate and other assets
Segment reporting information, revenues
Rental revenues	0			0			0	0
Operating expenses	0			0			0	0
Segment NOI	0			0			0	0
Adjustments to NOI	0			0			0	0
Adjusted NOI	0			0			0	0
Addback adjustments	0			0			0	0
Interest income	0			0			0	0
Interest expense	(58,311)			(62,004)			(161,433)	(205,688)
Depreciation and amortization	0			0			0	0
General and administrative	(22,970)			(23,503)			(71,445)	(75,192)
Transaction costs	(1,319)			(4,489)			(7,174)	(9,088)
Recoveries (impairments), net	0			0			0	0
Gain (loss) on sales of real estate, net	0			0			0	0
Loss on debt extinguishments	(35,017)			(43,899)			(36,152)	(43,899)
Other income (expense), net	(287)			1,604			11,037	3,550
Income tax benefit (expense)	6,261			4,929			11,583	14,919
Equity income (loss) from unconsolidated joint ventures	0			0			0	0
Net income (loss)	$ (111,643)			$ (127,362)			$ (253,584)	$ (315,398)
Senior housing triple-net
Segment Disclosure
Number of facilities transitioned | facility	0			6			39	16
Segment reporting information, revenues
Gain (loss) on sales of real estate, net					$ 25,000
Senior housing triple-net | Operating segment
Segment reporting information, revenues
Rental revenues	$ 48,018			$ 67,487			$ 156,776	$ 212,489
Operating expenses	(865)			(840)			(2,723)	(2,677)
Segment NOI	47,153			66,647			154,053	209,812
Adjustments to NOI	(1,537)			534			3,833	(323)
Adjusted NOI	45,616			67,181			157,886	209,489
Addback adjustments	1,537			(534)			(3,833)	323
Interest income	0			0			0	0
Interest expense	(106)			(599)			(901)	(1,806)
Depreciation and amortization	(12,778)			(18,884)			(45,154)	(62,041)
General and administrative	0			0			0	0
Transaction costs	0			0			0	0
Recoveries (impairments), net	(7,430)			0			(22,914)	(6,273)
Gain (loss) on sales of real estate, net	0			463			3,557	(22,687)
Loss on debt extinguishments	0			0			0	0
Other income (expense), net	0			0			0	0
Income tax benefit (expense)	0			0			0	0
Equity income (loss) from unconsolidated joint ventures	0			0			0	0
Net income (loss)	26,839			47,627			88,641	117,005
SHOP
Segment reporting information, revenues
Gain (loss) on sales of real estate, net						$ 21,000
SHOP | Operating segment
Segment reporting information, revenues
Rental revenues	212,275			137,044			515,457	420,067
Operating expenses	(166,201)			(106,182)			(400,608)	(309,694)
Segment NOI	46,074			30,862			114,849	110,373
Adjustments to NOI	740			1,378			2,732	(356)
Adjusted NOI	46,814			32,240			117,581	110,017
Addback adjustments	(740)			(1,378)			(2,732)	356
Interest income	0			0			0	0
Interest expense	(2,637)			(688)			(4,626)	(2,067)
Depreciation and amortization	(58,152)			(25,166)			(134,481)	(80,797)
General and administrative	0			0			0	0
Transaction costs	0			0			0	0
Recoveries (impairments), net	(24,721)			(5,268)			(77,685)	(5,268)
Gain (loss) on sales of real estate, net	(734)			10,163			8,844	79,340
Loss on debt extinguishments	0			0			0	0
Other income (expense), net	0			0			0	0
Income tax benefit (expense)	0			0			0	0
Equity income (loss) from unconsolidated joint ventures	0			0			0	0
Net income (loss)	(40,170)			9,903			(93,099)	101,581
Life science | Operating segment
Segment reporting information, revenues
Rental revenues	118,561			98,040			320,630	298,692
Operating expenses	(29,520)			(23,668)			(76,992)	(68,208)
Segment NOI	89,041			74,372			243,638	230,484
Adjustments to NOI	(7,067)			(1,439)			(17,159)	(7,423)
Adjusted NOI	81,974			72,933			226,479	223,061
Addback adjustments	7,067			1,439			17,159	7,423
Interest income	0			0			0	0
Interest expense	(68)			(78)			(211)	(240)
Depreciation and amortization	(45,028)			(34,432)			(122,705)	(105,782)
General and administrative	0			0			0	0
Transaction costs	0			0			0	0
Recoveries (impairments), net	0			0			0	(7,639)
Gain (loss) on sales of real estate, net	(87)			80,580			3,651	80,581
Loss on debt extinguishments	0			0			0	0
Other income (expense), net	0			0			0	0
Income tax benefit (expense)	0			0			0	0
Equity income (loss) from unconsolidated joint ventures	0			0			0	0
Net income (loss)	43,858			120,442			$ 124,373	197,404
Medical office
Segment Disclosure
Number of facilities transitioned | facility			2				2
Medical office | Operating segment
Segment reporting information, revenues
Rental revenues	143,639			139,566			$ 427,761	407,361
Operating expenses	(51,472)			(50,478)			(150,635)	(146,881)
Segment NOI	92,167			89,088			277,126	260,480
Adjustments to NOI	(1,568)			(1,364)			(4,542)	(5,129)
Adjusted NOI	90,599			87,724			272,584	255,351
Addback adjustments	1,568			1,364			4,542	5,129
Interest income	0			0			0	0
Interest expense	(108)			(117)			(328)	(356)
Depreciation and amortization	(54,152)			(51,977)			(161,350)	(147,270)
General and administrative	0			0			0	0
Transaction costs	0			0			0	0
Recoveries (impairments), net	(5,729)			0			(14,677)	0
Gain (loss) on sales of real estate, net	(7)			3,903			2,876	3,903
Loss on debt extinguishments	0			0			0	0
Other income (expense), net	0			0			0	0
Income tax benefit (expense)	0			0			0	0
Equity income (loss) from unconsolidated joint ventures	0			0			0	0
Net income (loss)	32,171			40,897			103,647	116,757
Other non-reportable segments | Operating segment
Segment reporting information, revenues
Rental revenues	12,737			12,649			38,200	57,113
Operating expenses	(11)			(39)			(31)	(165)
Segment NOI	12,726			12,610			38,169	56,948
Adjustments to NOI	469			188			884	(820)
Adjusted NOI	13,195			12,798			39,053	56,128
Addback adjustments	(469)			(188)			(884)	820
Interest income	2,741			1,236			6,868	9,048
Interest expense	0			0			0	(1,469)
Depreciation and amortization	(1,834)			(1,739)			(5,501)	(22,850)
General and administrative	0			0			0	0
Transaction costs	0			0			0	0
Recoveries (impairments), net	(377)			0			(377)	0
Gain (loss) on sales of real estate, net	44			223			(220)	21,074
Loss on debt extinguishments	0			0			0	0
Other income (expense), net	980			0			13,797	(40,567)
Income tax benefit (expense)	0			0			0	0
Equity income (loss) from unconsolidated joint ventures	(7,643)			(911)			(10,012)	(442)
Net income (loss)	$ 6,637			$ 11,419			$ 42,724	$ 21,742