Real Estate and Lending Activities - Concentration of Credit Risks and Related Party Transactions - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) Investment	Mar. 31, 2018 USD ($)	Dec. 31, 2018
Business Acquisition [Line Items]
Revenue from affiliates of total revenue	$ 180,454	$ 205,046
Total Gross Assets [Member] | Geographic Concentration [Member] | U.S. [Member]
Business Acquisition [Line Items]
Percentage of revenue from affiliates of total revenue	80.00%		80.00%
Total Gross Assets [Member] | Geographic Concentration [Member] | Europe [Member]
Business Acquisition [Line Items]
Percentage of revenue from affiliates of total revenue	20.00%		20.00%
Revenue [Member] | Customer Concentration Risk [Member] | General Acute Care Hospital and Healthcare System [Member]
Business Acquisition [Line Items]
Percentage of revenue from affiliates of total revenue	86.00%	86.00%
Revenue [Member] | Customer Concentration Risk [Member] | Rehabilitation Hospital with Covenant Health System [Member]
Business Acquisition [Line Items]
Percentage of revenue from affiliates of total revenue	10.00%	10.00%
Revenue [Member] | Customer Concentration Risk [Member] | Long-term Acute Care Hospital [Member]
Business Acquisition [Line Items]
Percentage of revenue from affiliates of total revenue	4.00%	4.00%
Revenue [Member] | Credit Concentration Risk [Member] | Steward [Member]
Business Acquisition [Line Items]
Revenue from affiliates of total revenue	$ 86,600	$ 73,200
Revenue [Member] | Credit Concentration Risk [Member] | Prime [Member]
Business Acquisition [Line Items]
Revenue from affiliates of total revenue	$ 32,000	31,800
Revenue [Member] | Credit Concentration Risk [Member] | MEDIAN [Member]
Business Acquisition [Line Items]
Revenue from affiliates of total revenue		$ 29,100
Pro Forma [Member] | Total Gross Assets [Member] | Customer Concentration Risk [Member]
Business Acquisition [Line Items]
Number of investment in property | Investment	0
Maximum percentage of entity's assets invested on single property	4.00%