Relationship with Universal Health Services, Inc. ("UHS") and Related Party Transactions - Additional Information (Detail)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2020 USD ($) Property Time Lease	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Property Time Lease	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Related Party Transaction [Line Items]
Annual advisory fee as percentage of average invested real estate assets		0.70%	0.70%	0.70%	0.70%
Universal Health Services, Inc
Related Party Transaction [Line Items]
Number of term renewal options | Time		6		6
Additional renewal terms				5 years
Number of medical office buildings and free standing emergency departments | Property				17
Option to renew lease, notice period prior to termination date of current term				90 days
Period to purchase respective leased facilities at same price after lease terms				180 days
Renewal period of respective leased facilities at same price after lease terms				180 days
Number of renewal options at existing lease rate | Time				3
Lease revenue	[1]	$ 6,381,000	$ 5,821,000	$ 18,243,000	$ 17,265,000
Number of ground leases | Lease		11		11
Aggregate lease payments for 2020		$ 482,000		$ 482,000
Aggregate lease payments for 2021		482,000		482,000
Aggregate lease payments for 2022		482,000		482,000
Aggregate lease payments for 2023		482,000		482,000
Aggregate lease payments for 2024		482,000		482,000
Aggregate lease payments for thereafter		$ 27,500,000		$ 27,500,000
Percentage ownership of outstanding shares		5.70%		5.70%		5.70%
Universal Health Services, Inc | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Lease expiration date				Dec. 31, 2021
Lease revenue				$ 3,300,000		$ 4,300,000
Universal Health Services, Inc | Base Rents
Related Party Transaction [Line Items]
Lease revenue		$ 4,402,000	4,159,000	12,940,000	12,448,000
Universal Health Services, Inc | Base Rents | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Lease revenue				2,000,000.0		2,600,000
Universal Health Services, Inc | Bonus Rents
Related Party Transaction [Line Items]
Lease revenue		$ 1,680,000	$ 1,428,000	4,477,000	$ 4,174,000
Universal Health Services, Inc | Bonus Rents | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Lease revenue				$ 1,300,000		$ 1,700,000
Universal Health Services, Inc | Customer Concentration Risk | Revenues
Related Party Transaction [Line Items]
Percentage of revenues generated from leases and tenants		23.00%	21.00%	22.00%	22.00%
Universal Health Services, Inc | Customer Concentration Risk | Revenues | Tenants
Related Party Transaction [Line Items]
Percentage of revenues generated from leases and tenants		34.00%	30.00%	33.00%	31.00%
Universal Health Services, Inc | Hospital Facilities Leased
Related Party Transaction [Line Items]
Number of acute care hospitals | Property		3		3
Universal Health Services, Inc | Minimum
Related Party Transaction [Line Items]
Initial lease terms				13 years
Remaining lease terms on ground leases				29 years
Universal Health Services, Inc | Maximum
Related Party Transaction [Line Items]
Initial lease terms				15 years
Remaining lease terms on ground leases				79 years
Universal Health Services of Delaware Inc
Related Party Transaction [Line Items]
Advisory fee		$ 1,000,000.0	$ 1,000,000.0	$ 3,100,000	$ 3,000,000.0
Cost, Product and Service [Extensible List]		us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Average invested real estate assets		$ 594,000,000	$ 578,000,000	$ 587,000,000	$ 564,000,000

[1] Includes bonus rental on UHS hospital facilities of $1,680 and $1,428 for the three-month periods ended September 30, 2020 and 2019, respectively, and $4,477 and $4,174 for the nine-month periods ended September 30, 2020 and 2019, respectively.