Segment Disclosures - Summary Information for the Reportable Segments (Details) - USD ($)	1 Months Ended		3 Months Ended								12 Months Ended
	Mar. 31, 2017	Jan. 31, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment reporting information, revenues
Rental estate revenues											$ 1,987,539,000	$ 1,836,283,000	$ 1,792,141,000
Operating expenses											(879,370,000)	(705,038,000)	(666,251,000)
NOI											1,108,169,000	1,131,245,000	1,125,890,000
Adjustments to NOI											(21,058,000)	(11,904,000)	38,410,000
Adjusted NOI											1,087,111,000	1,119,341,000	1,164,300,000
Addback adjustments											21,058,000	11,904,000	(38,410,000)
Interest income											9,844,000	10,406,000	56,237,000
Interest expense											(225,619,000)	(266,343,000)	(307,716,000)
Depreciation and amortization											(659,989,000)	(549,499,000)	(534,726,000)
General and administrative											(92,966,000)	(96,702,000)	(88,772,000)
Transaction costs											(8,743,000)	(10,772,000)	(7,963,000)
Recoveries (impairments), net											(225,937,000)	(55,260,000)	(166,384,000)
Gain (loss) on sales of real estate, net			$ 11,000,000	$ 0	$ 11,000,000	$ 8,000,000		$ 95,000,000	$ 25,000,000		22,900,000	925,985,000	356,641,000
Loss on debt extinguishment											(58,364,000)	(44,162,000)	(54,227,000)
Other income (expense), net											182,129,000	13,316,000	31,420,000
Income tax benefit (expense)											17,262,000	17,854,000	1,333,000
Equity income (loss) from unconsolidated joint ventures											(8,625,000)	(2,594,000)	10,901,000
Discontinued operations													0
Net income (loss)			$ 47,359,000	$ (42,308,000)	(9,980,000)	$ 64,990,000	$ 834,383,000	$ 102,926,000	$ 92,928,000	$ 43,237,000	60,061,000	1,073,474,000	422,634,000
Corporate Non-segment
Segment reporting information, revenues
Rental estate revenues											0	0	0
Operating expenses											0	0	0
NOI											0	0	0
Adjustments to NOI											0	0	0
Adjusted NOI											0	0	0
Addback adjustments											0	0	0
Interest income											0	0	0
Interest expense											(216,386,000)	(258,955,000)	(292,169,000)
Depreciation and amortization											0	0	0
General and administrative											(92,966,000)	(96,702,000)	(88,772,000)
Transaction costs											(8,743,000)	(10,772,000)	(7,963,000)
Recoveries (impairments), net											0	0	0
Gain (loss) on sales of real estate, net											0	0	0
Loss on debt extinguishment											(58,364,000)	(44,162,000)	(54,227,000)
Other income (expense), net											13,106,000	3,711,000	(19,475,000)
Income tax benefit (expense)											17,262,000	17,854,000	1,333,000
Equity income (loss) from unconsolidated joint ventures											0	0	0
Discontinued operations													0
Net income (loss)											(346,091,000)	(389,026,000)	(461,273,000)
Senior housing triple-net
Segment reporting information, revenues
Recoveries (impairments), net													(23,000,000)
Gain (loss) on sales of real estate, net	$ 170,000,000
Senior housing triple-net | Operating segment
Segment reporting information, revenues
Rental estate revenues											199,441,000	276,091,000	313,547,000
Operating expenses											(4,565,000)	(3,618,000)	(3,819,000)
NOI											194,876,000	272,473,000	309,728,000
Adjustments to NOI											2,725,000	2,127,000	17,098,000
Adjusted NOI											197,601,000	274,600,000	326,826,000
Addback adjustments											(2,725,000)	(2,127,000)	(17,098,000)
Interest income											0	0	0
Interest expense											(1,003,000)	(2,404,000)	(2,518,000)
Depreciation and amortization											(55,361,000)	(79,605,000)	(103,820,000)
General and administrative											0	0	0
Transaction costs											0	0	0
Recoveries (impairments), net											(43,859,000)	0	(22,590,000)
Gain (loss) on sales of real estate, net											3,557,000	641,000	280,349,000
Loss on debt extinguishment											0	0	0
Other income (expense), net											0	0	0
Income tax benefit (expense)											0	0	0
Equity income (loss) from unconsolidated joint ventures											0	0	0
Discontinued operations													0
Net income (loss)											98,210,000	191,105,000	461,149,000
SHOP
Segment reporting information, revenues
Recoveries (impairments), net					$ (10,000,000)							(52,000,000)
Gain (loss) on sales of real estate, net										$ 21,000,000
SHOP | Operating segment
Segment reporting information, revenues
Rental estate revenues											725,171,000	547,976,000	525,473,000
Operating expenses											(565,713,000)	(414,312,000)	(396,491,000)
NOI											159,458,000	133,664,000	128,982,000
Adjustments to NOI											2,872,000	2,875,000	33,227,000
Adjusted NOI											162,330,000	136,539,000	162,209,000
Addback adjustments											(2,872,000)	(2,875,000)	(33,227,000)
Interest income											0	0	0
Interest expense											(7,519,000)	(2,725,000)	(7,920,000)
Depreciation and amortization											(214,590,000)	(104,405,000)	(103,162,000)
General and administrative											0	0	0
Transaction costs											0	0	0
Recoveries (impairments), net											(164,369,000)	(44,343,000)	0
Gain (loss) on sales of real estate, net											19,384,000	93,977,000	17,485,000
Loss on debt extinguishment											0	0	0
Other income (expense), net											160,886,000	0	0
Income tax benefit (expense)											0	0	0
Equity income (loss) from unconsolidated joint ventures											0	0	0
Discontinued operations													0
Net income (loss)											(46,750,000)	76,168,000	35,385,000
Life science
Segment reporting information, revenues
Gain (loss) on sales of real estate, net		$ 45,000,000
Life science | Operating segment
Segment reporting information, revenues
Rental estate revenues											440,784,000	395,064,000	358,816,000
Operating expenses											(107,472,000)	(91,742,000)	(78,001,000)
NOI											333,312,000	303,322,000	280,815,000
Adjustments to NOI											(22,120,000)	(9,589,000)	(4,517,000)
Adjusted NOI											311,192,000	293,733,000	276,298,000
Addback adjustments											22,120,000	9,589,000	4,517,000
Interest income											0	0	0
Interest expense											(277,000)	(316,000)	(373,000)
Depreciation and amortization											(168,339,000)	(140,480,000)	(128,864,000)
General and administrative											0	0	0
Transaction costs											0	0	0
Recoveries (impairments), net											0	(7,639,000)	0
Gain (loss) on sales of real estate, net											3,651,000	806,184,000	45,916,000
Loss on debt extinguishment											0	0	0
Other income (expense), net											0	0	0
Income tax benefit (expense)											0	0	0
Equity income (loss) from unconsolidated joint ventures											0	0	0
Discontinued operations													0
Net income (loss)											168,347,000	961,071,000	197,494,000
Medical office
Segment reporting information, revenues
Recoveries (impairments), net											(4,000,000)
Gain (loss) on sales of real estate, net													41,000,000
Medical office | Operating segment
Segment reporting information, revenues
Rental estate revenues											571,530,000	547,375,000	512,385,000
Operating expenses											(201,538,000)	(195,100,000)	(187,688,000)
NOI											369,992,000	352,275,000	324,697,000
Adjustments to NOI											(5,877,000)	(6,690,000)	(5,405,000)
Adjusted NOI											364,115,000	345,585,000	319,292,000
Addback adjustments											5,877,000	6,690,000	5,405,000
Interest income											0	0	0
Interest expense											(434,000)	(474,000)	(506,000)
Depreciation and amortization											(214,669,000)	(200,430,000)	(176,507,000)
General and administrative											0	0	0
Transaction costs											0	0	0
Recoveries (impairments), net											(17,332,000)	0	0
Gain (loss) on sales of real estate, net											3,139,000	4,428,000	9,095,000
Loss on debt extinguishment											0	0	0
Other income (expense), net											0	0	0
Income tax benefit (expense)											0	0	0
Equity income (loss) from unconsolidated joint ventures											0	0	0
Discontinued operations													0
Net income (loss)											140,696,000	155,799,000	156,779,000
Other non-reportable segments | Operating segment
Segment reporting information, revenues
Rental estate revenues											50,613,000	69,777,000	81,920,000
Operating expenses											(82,000)	(266,000)	(252,000)
NOI											50,531,000	69,511,000	81,668,000
Adjustments to NOI											1,342,000	(627,000)	(1,993,000)
Adjusted NOI											51,873,000	68,884,000	79,675,000
Addback adjustments											(1,342,000)	627,000	1,993,000
Interest income											9,844,000	10,406,000	56,237,000
Interest expense											0	(1,469,000)	(4,230,000)
Depreciation and amortization											(7,030,000)	(24,579,000)	(22,373,000)
General and administrative											0	0	0
Transaction costs											0	0	0
Recoveries (impairments), net											(377,000)	(3,278,000)	(143,794,000)
Gain (loss) on sales of real estate, net											(6,831,000)	20,755,000	3,796,000
Loss on debt extinguishment											0	0	0
Other income (expense), net											8,137,000	9,605,000	50,895,000
Income tax benefit (expense)											0	0	0
Equity income (loss) from unconsolidated joint ventures											(8,625,000)	(2,594,000)	10,901,000
Discontinued operations													0
Net income (loss)											$ 45,649,000	$ 78,357,000	$ 33,100,000