Real Estate and Lending Activities - Concentration of Credit Risks and Related Party Transactions - Additional Information (Detail)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Total Gross Assets [Member] | Geographic Concentration [Member] | U.S. [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	70.00%		74.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | Europe [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	25.00%		20.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | Australia [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	5.00%		6.00%
Revenue [Member] | Customer Concentration Risk [Member] | General Acute Care Hospital and Healthcare System [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	89.00%
Revenue [Member] | Customer Concentration Risk [Member] | Rehabilitation Hospital with Covenant Health System [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	8.00%
Revenue [Member] | Customer Concentration Risk [Member] | Long-term Acute Care Hospital [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	3.00%
Revenue [Member] | Credit Concentration Risk [Member] | Steward [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	30.00%	44.00%
Revenue [Member] | Credit Concentration Risk [Member] | Circle [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	13.00%
Revenue [Member] | Credit Concentration Risk [Member] | Prospect [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	13.00%
Revenue [Member] | Credit Concentration Risk [Member] | Prime Healthcare Services [Member]
Business Acquisition [Line Items]
Percentage of concentration risk	11.00%	16.00%
Revenue [Member] | Credit Concentration Risk [Member] | Prospect and Circle [Member] | Maximum [Member]
Business Acquisition [Line Items]
Percentage of concentration risk		4.00%
Pro Forma [Member] | Total Gross Assets [Member] | Customer Concentration Risk [Member]
Business Acquisition [Line Items]
Largest percentage of entity's assets invested on single property	3.00%