New Construction, Acquisitions and Dispositions - Additional Information (Detail)	1 Months Ended			9 Months Ended
	Apr. 30, 2020 ft²	Sep. 30, 2019 USD ($) ft²	Jul. 31, 2019 USD ($) Time	Sep. 30, 2020 USD ($) Time Acquisition Disposition	Sep. 30, 2019 USD ($) ft² Acquisition Disposition
Business Acquisitions And Dispositions [Line Items]
Outstanding loan balance				$ 10,400
Construction loan scheduled maturity		Jun. 01, 2025
Number of acquisitions | Acquisition				0	0
Number of dispositions | Disposition				0	0
Medical Office Buildings Third Floor
Business Acquisitions And Dispositions [Line Items]
Rentable square feet reduced in master flex lease commitment | ft²	20,000
Medical office buildings
Business Acquisitions And Dispositions [Line Items]
Third-party tenant lease term	122 months
Medical Office Buildings First Floor
Business Acquisitions And Dispositions [Line Items]
Percentage of rentable square feet	61.00%
Universal Health Services, Inc
Business Acquisitions And Dispositions [Line Items]
Master flex lease term		10 years
Rentable square feet | ft²		40,000			40,000
Percentage of rentable square feet		50.00%
Number of term renewal options | Time				6
Universal Health Services, Inc | Medical Office Buildings Third Floor
Business Acquisitions And Dispositions [Line Items]
Rentable square feet | ft²		20,000			20,000
Universal Health Services, Inc | Maximum | Medical Office Buildings First and Second Floor
Business Acquisitions And Dispositions [Line Items]
Rentable square feet | ft²		20,000			20,000
Third-Party Tenant
Business Acquisitions And Dispositions [Line Items]
Construction loan		$ 13,100			$ 13,100
Third-Party Tenant | Medical Office Buildings First Floor
Business Acquisitions And Dispositions [Line Items]
Rentable square feet | ft²	26,000
Universal Health Services, Inc and Catholic Health Initiatives
Business Acquisitions And Dispositions [Line Items]
Triple net lease agreement period			20 years
Number of term renewal options | Time			5
Renewal option term			10 years
Project manager's aggregate fee			$ 750,000
Estimated approximate project cost			37,500,000
Estimated initial annual rent			$ 2,700,000
Des Moines Medical Properties, LLC
Business Acquisitions And Dispositions [Line Items]
Land and development and construction costs				$ 25,000,000.0
Grayson Properties II LP | Medical office buildings
Business Acquisitions And Dispositions [Line Items]
Committed investment in equity or member loans		0			0
Grayson Properties II LP | Maximum | Medical office buildings
Business Acquisitions And Dispositions [Line Items]
Commitment to investment		$ 4,800			$ 4,800
Grayson Properties II LP | Denison, Texas
Business Acquisitions And Dispositions [Line Items]
Non-controlling equity interest, ownership percentage		95.00%			95.00%