Real Estate and Lending Activities - 2019 Activity - Additional Information (Detail) £ in Millions, SFr in Millions, $ in Millions								9 Months Ended
	Aug. 30, 2019 USD ($) RenewalOption	Aug. 23, 2019 USD ($) Hospital RenewalOption Health_Center	Aug. 16, 2019 GBP (£) Hospital	Jun. 28, 2019 CHF (SFr)	Jun. 10, 2019 USD ($) Hospital RenewalOption	Jun. 06, 2019 AUD ($) Hospital	May 27, 2019 CHF (SFr) _Campus	Sep. 30, 2020 USD ($) Hospital	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Mortgage loan balance								$ 1,512,946,000	$ 1,819,854,000
Term of lease								15 years
Term of lease extension, years								5 years
Other Acquisitions [Member]
Business Acquisition [Line Items]
Purchase price of acquisition								$ 135,000,000
Vibra Healthcare, LLC [Member]
Business Acquisition [Line Items]
Purchase price of acquisition	$ 254,000,000
Term of lease	20 years
Number of lease extension options | RenewalOption	3
Existence of option to extend	true
Lease extension options, description								three five-year extension options
Term of lease extension, years	5 years
Ramsay Health Care [Member]
Business Acquisition [Line Items]
Term of lease			18 years
Swiss Healthcare Real Estate Company Infracore S A [Member] | Joint Venture Partner [Member]
Business Acquisition [Line Items]
Ownership interest in joint venture under the equity method							40.00%
Swiss Healthcare Real Estate Company Infracore S A [Member] | Switzerland [Member]
Business Acquisition [Line Items]
Purchase price of acquisition | SFr							SFr 236.6
Swiss Medical Network [Member]
Business Acquisition [Line Items]
Weighted average remaining lease term							23 years
Aevis Victoria SA [Member]
Business Acquisition [Line Items]
Purchase price of acquisition | SFr				SFr 47.0
Ownership interest in joint venture under the cost method				4.90%
Prospect [Member]
Business Acquisition [Line Items]
Purchase price of acquisition		$ 1,550,000,000
Term loan		$ 112,900,000
Additional number of businesses acquired | Hospital		2
Term of lease		15 years
Number of lease extension options | RenewalOption		3
Existence of option to extend		true
Future purchase price adjustment		$ 250,000,000.0
Performance thresholds achievement period		3 years
Prospect [Member] | Investment in Financing Leases [Member]
Business Acquisition [Line Items]
Purchase price of acquisition		$ 1,400,000,000
Secure Income REIT [Member]
Business Acquisition [Line Items]
Purchase price of acquisition | £			£ 347
Secure Income REIT [Member] | United Kingdom [Member]
Business Acquisition [Line Items]
Number of private hospitals acquired | Hospital			8
Acute Care Campus [Member] | Swiss Healthcare Real Estate Company Infracore S A [Member] | Switzerland [Member]
Business Acquisition [Line Items]
Number of facilities acquired | _Campus							13
Acute Care Campus [Member] | Prospect [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital		14
Acute Care Campus [Member] | Prospect [Member] | Investment in Financing Leases [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital		11
Behavioral Health Care Facility [Member] | Prospect [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Health_Center		2
Behavioral Health Care Facility [Member] | Prospect [Member] | Investment in Financing Leases [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Health_Center		2
Acute Care Hospital [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								2
Acute Care Hospital [Member] | Poole, England [Member] | Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								3
Acute Care Hospital [Member] | Prospect [Member] | Mortgage Loans [Member]
Business Acquisition [Line Items]
Mortgage loan balance		$ 51,300,000
Community Hospital [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital					7
Number of lease extension options | RenewalOption					2
Term of lease extension, years					5 years
Leases fixed escalations					5 years
Lease extension options, description								two five-year extension options
Existence of option to extend					true
Community Hospital [Member] | Kansas [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital					7
Purchase price of acquisition					$ 145,400,000
Community Hospital [Member] | Saint Luke's Health System [Member]
Business Acquisition [Line Items]
Term of lease					14 years
Hospital [Member] | Australia [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital						11
Purchase price of acquisition						$ 1,200.0
Stamp duties and registration fees						$ 66.6
Hospital [Member] | Healthscope Limited [Member]
Business Acquisition [Line Items]
Term of lease						20 years
Additional Properties [Member] | Swiss Healthcare Real Estate Company Infracore S A [Member] | Switzerland [Member]
Business Acquisition [Line Items]
Number of facilities acquired | _Campus							2
Inpatient Rehabilitation Hospital [Member] | Germany [Member] | Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								1