Real Estate and Other Activities - Concentrations of Credit Risk - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Total Gross Assets [Member] | Geographic Concentration [Member] | U.S. [Member]
Business Acquisition [Line Items]
Percentage of concentration risk			65.00%		65.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | Europe [Member]
Business Acquisition [Line Items]
Percentage of concentration risk			29.00%		28.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | Australia [Member]
Business Acquisition [Line Items]
Percentage of concentration risk			5.00%		6.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | South America [Member]
Business Acquisition [Line Items]
Percentage of concentration risk			1.00%		1.00%
Revenue [Member] | Customer Concentration Risk [Member] | General Acute Care Facilities [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	80.00%	80.00%	80.00%	80.00%
Revenue [Member] | Customer Concentration Risk [Member] | Rehabilitation Facilities [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Customer Concentration Risk [Member] | Behavioral Health, Freestanding ER/Urgent Care And Long-Term Acute Care Facilities [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Operator Concentration Risk [Member] | Steward Health Care System LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Operator Concentration Risk [Member] | Prospect [Member] | Minimum [Member]
Business Acquisition [Line Items]
Percentage of concentration risk		10.00%		10.00%
Revenue [Member] | Operator Concentration Risk [Member] | Circle [Member] | Minimum [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Operator Concentration Risk [Member] | Prime Healthcare Services [Member] | Minimum [Member]
Business Acquisition [Line Items]
Percentage of concentration risk		10.00%		10.00%
Pro Forma [Member] | Total Gross Assets [Member] | Customer Concentration Risk [Member]
Business Acquisition [Line Items]
Maximum percentage of entity's assets invested on single property	3.00%		3.00%		3.00%