Real Estate Properties - Schedule of Acquisitions (Details) $ in Thousands		1 Months Ended											12 Months Ended
	Dec. 31, 2017 USD ($) property	Dec. 31, 2019 USD ($) living_unit property	Mar. 31, 2019 ft²	Jun. 30, 2018 USD ($) living_unit property	Mar. 31, 2018 USD ($) property	Feb. 28, 2018 USD ($) living_unit property	Jan. 31, 2018 USD ($) ft² living_unit property	Dec. 31, 2017 USD ($) ft² living_unit property	Nov. 30, 2017 USD ($) ft² property	Oct. 31, 2017 USD ($) ft² property	Jul. 31, 2017 USD ($) ft² property	Jan. 31, 2017 USD ($) ft² property	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property
Real Estate [Line Items]
Net Book Value of Collateral		$ 5,890,785											$ 5,890,785	$ 6,341,908
Assumed Debt													$ 0	$ (44,386)	$ 0
Acquisitions
Real Estate [Line Items]
Number of Properties | property													8		8
Cash Paid Plus Assumed Debt													$ 181,323		$ 152,625
Acquired Real Estate Leases / Resident Agreements	$ 35,487	41,016						$ 35,487					41,016		35,487
Acquired Real Estate Lease Obligations	(20)	$ 0						$ (20)					0		(20)
Assumed Debt													(44,386)		0
Premium on Assumed Debt													(1,845)		0
Medical Office and Life Science | 3 States | Acquisitions
Real Estate [Line Items]
Number of Properties | property							3
Square Footage Of Properties Acquired | ft²							400,000
Cash Paid Plus Assumed Debt							$ 91,698
Acquired Real Estate Leases / Resident Agreements							20,220
Acquired Real Estate Lease Obligations							0
Assumed Debt							0
Premium on Assumed Debt							$ 0
Medical Office and Life Science | 2 States | Acquisitions
Real Estate [Line Items]
Number of Properties | property										2
Square Footage Of Properties Acquired | ft²										255,000
Cash Paid Plus Assumed Debt										$ 38,794
Acquired Real Estate Leases / Resident Agreements										7,016
Acquired Real Estate Lease Obligations										0
Assumed Debt										0
Premium on Assumed Debt										0
Medical Office
Real Estate [Line Items]
Number of Properties | property														13
Medical Office | Virginia | Acquisitions
Real Estate [Line Items]
Number of Properties | property					1			1
Square Footage Of Properties Acquired | ft²			135,000					136,000
Cash Paid Plus Assumed Debt					$ 23,275			$ 15,844
Acquired Real Estate Leases / Resident Agreements	4,986				9,307			4,986							4,986
Acquired Real Estate Lease Obligations	$ (20)				0			(20)							(20)
Assumed Debt					(11,050)			0
Premium on Assumed Debt					0			$ 0
Medical Office | Kansas | Acquisitions
Real Estate [Line Items]
Number of Properties | property												1
Square Footage Of Properties Acquired | ft²												117,000
Cash Paid Plus Assumed Debt												$ 15,106
Acquired Real Estate Leases / Resident Agreements												6,338
Acquired Real Estate Lease Obligations												0
Assumed Debt												0
Premium on Assumed Debt												0
Medical Office | California | Acquisitions
Real Estate [Line Items]
Number of Properties | property									1
Square Footage Of Properties Acquired | ft²									63,000
Cash Paid Plus Assumed Debt									$ 26,823
Acquired Real Estate Leases / Resident Agreements									5,436
Acquired Real Estate Lease Obligations									0
Assumed Debt									0
Premium on Assumed Debt									0
Life Science | Maryland | Acquisitions
Real Estate [Line Items]
Number of Properties | property											1
Square Footage Of Properties Acquired | ft²											59,000
Cash Paid Plus Assumed Debt											$ 16,601
Acquired Real Estate Leases / Resident Agreements											3,937
Acquired Real Estate Lease Obligations											0
Assumed Debt											0
Premium on Assumed Debt											0
Independent Living | Texas | Acquisitions
Real Estate [Line Items]
Number of Properties | property		1
Number of Units | living_unit		169
Cash Paid Plus Assumed Debt		$ 50,506
Acquired Real Estate Leases / Resident Agreements		2,202											2,202
Acquired Real Estate Lease Obligations		0											0
Assumed Debt		0
Premium on Assumed Debt		0
Independent Living | Tennessee | Acquisitions
Real Estate [Line Items]
Number of Properties | property				2
Number of Units | living_unit				151
Cash Paid Plus Assumed Debt				$ 23,860
Acquired Real Estate Leases / Resident Agreements				3,843
Acquired Real Estate Lease Obligations				0
Assumed Debt				(16,588)
Premium on Assumed Debt				(486)
Independent Living | Arizona | Acquisitions
Real Estate [Line Items]
Number of Properties | property						1
Number of Units | living_unit						127
Cash Paid Plus Assumed Debt						$ 22,622
Acquired Real Estate Leases / Resident Agreements						4,451
Acquired Real Estate Lease Obligations						0
Assumed Debt						(16,748)
Premium on Assumed Debt						(1,359)
Assisted Living | Tennessee | Acquisitions
Real Estate [Line Items]
Number of Properties | property							1
Number of Units | living_unit							88
Cash Paid Plus Assumed Debt							$ 19,868
Acquired Real Estate Leases / Resident Agreements							3,195
Acquired Real Estate Lease Obligations							0
Assumed Debt							0
Premium on Assumed Debt							0
Independent Living and Assisted Living | 2 States | Acquisitions
Real Estate [Line Items]
Number of Properties | property	2
Number of Units | living_unit								229
Cash Paid Plus Assumed Debt								$ 39,457
Acquired Real Estate Leases / Resident Agreements	$ 7,774							7,774							7,774
Acquired Real Estate Lease Obligations	0							0							0
Assumed Debt								0
Premium on Assumed Debt								0
Land
Real Estate [Line Items]
Net Book Value of Collateral		793,123											793,123	$ 844,567
Land | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	29,673	23,298						29,673					23,298		29,673
Land | Medical Office and Life Science | 3 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							16,873
Land | Medical Office and Life Science | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral										6,738
Land | Medical Office | Virginia | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	3,263				2,863			3,263							3,263
Land | Medical Office | Kansas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral												1,522
Land | Medical Office | California | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral									7,957
Land | Life Science | Maryland | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral											6,138
Land | Independent Living | Texas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral		3,463											3,463
Land | Independent Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral				965
Land | Independent Living | Arizona | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral						2,017
Land | Assisted Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							580
Land | Independent Living and Assisted Living | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	4,055							4,055							4,055
Buildings and Improvements
Real Estate [Line Items]
Net Book Value of Collateral		6,668,463											6,668,463	$ 7,031,733
Buildings and Improvements | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	86,281	115,627						86,281					115,627		86,281
Buildings and Improvements | Medical Office and Life Science | 3 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							54,605
Buildings and Improvements | Medical Office and Life Science | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral										25,040
Buildings and Improvements | Medical Office | Virginia | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	7,615				11,105			7,615							7,615
Buildings and Improvements | Medical Office | Kansas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral												7,246
Buildings and Improvements | Medical Office | California | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral									13,430
Buildings and Improvements | Life Science | Maryland | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral											6,526
Buildings and Improvements | Independent Living | Texas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral		44,189											44,189
Buildings and Improvements | Independent Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral				17,910
Buildings and Improvements | Independent Living | Arizona | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral						17,123
Buildings and Improvements | Assisted Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							14,884
Buildings and Improvements | Independent Living and Assisted Living | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	26,424							26,424							26,424
FF&E | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	1,204	3,227						1,204					3,227		1,204
FF&E | Medical Office and Life Science | 3 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							0
FF&E | Medical Office and Life Science | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral										$ 0
FF&E | Medical Office | Virginia | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	0				$ 0			0							0
FF&E | Medical Office | Kansas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral												$ 0
FF&E | Medical Office | California | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral									$ 0
FF&E | Life Science | Maryland | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral											$ 0
FF&E | Independent Living | Texas | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral		$ 652											$ 652
FF&E | Independent Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral				$ 1,628
FF&E | Independent Living | Arizona | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral						$ 390
FF&E | Assisted Living | Tennessee | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral							$ 1,209
FF&E | Independent Living and Assisted Living | 2 States | Acquisitions
Real Estate [Line Items]
Net Book Value of Collateral	$ 1,204							$ 1,204							$ 1,204