Relationship with Universal Health Services, Inc. ("UHS") and Related Party Transactions - Additional Information (Detail)		1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
		May 31, 2021 USD ($) Time	Sep. 30, 2019	Jul. 31, 2019 USD ($) Time	Sep. 30, 2021 USD ($) Property Time Lease	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Property Time Lease Hospital RenewalOption	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Nov. 08, 2021 USD ($)
Related Party Transaction [Line Items]
Annual advisory fee as percentage of average invested real estate assets					0.70%	0.70%	0.70%	0.70%
Grayson Properties | Subsequent Event
Related Party Transaction [Line Items]
Minority ownership interest held by a third-party										5.00%
Ownership percentage upon completion of the minority ownership purchase										100.00%
Minority ownership interest										$ 3,100,000
Grayson Properties Two L P | Denison Texas
Related Party Transaction [Line Items]
Non-controlling equity interest, ownership percentage			95.00%
Universal Health Services, Inc
Related Party Transaction [Line Items]
Number of term renewal options | Time		2			6		6
Additional renewal terms							5 years
Number of hospital facilities leased | Property					3		3
Number of medical office buildings and free standing emergency departments | Property							19
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 | Hospital							3
Lease revenue	[1]				$ 7,574,000	$ 6,381,000	$ 21,971,000	$ 18,243,000
Master flex lease term			10 years
Percentage of rentable square feet			50.00%
Number of ground leases | Lease					12		12
Aggregate lease payments for 2021					$ 508,000		$ 508,000
Aggregate lease payments for 2022					508,000		508,000
Aggregate lease payments for 2023					508,000		508,000
Aggregate lease payments for 2024					508,000		508,000
Aggregate lease payments for 2025					508,000		508,000
Aggregate lease payments for thereafter					$ 29,000,000.0		$ 29,000,000.0
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]
Number of renewal options at fair market value lease rates | RenewalOption							2
Renewal options term at fair market value lease rates							5 years
Lease expiration date							Dec. 31, 2021
Lease revenue							$ 3,400,000		$ 4,400,000
Universal Health Services, Inc | Base Rents
Related Party Transaction [Line Items]
Lease revenue					$ 5,392,000	4,402,000	15,820,000	12,940,000
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					$ 1,828,000	$ 1,680,000	5,171,000	$ 4,477,000
Universal Health Services, Inc | Bonus Rents | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Lease revenue							$ 1,400,000		$ 1,800,000
Universal Health Services, Inc | Customer Concentration Risk | Revenues
Related Party Transaction [Line Items]
Percentage of revenues generated from leases and tenants					22.00%	23.00%	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					37.00%	34.00%	36.00%	33.00%
Universal Health Services, Inc | Minimum
Related Party Transaction [Line Items]
Initial lease terms							13 years
Remaining lease terms on ground leases							28 years
Universal Health Services, Inc | Minimum | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Renewal options at fair market value lease rates expiration year							2022
Universal Health Services, Inc | Maximum
Related Party Transaction [Line Items]
Initial lease terms							15 years
Remaining lease terms on ground leases							78 years
Universal Health Services, Inc | Maximum | Southwest Healthcare System, Inland Valley Campus
Related Party Transaction [Line Items]
Renewal options at fair market value lease rates expiration year							2031
Fire Mesa Office Building [Member]
Related Party Transaction [Line Items]
Lease expiration date		Aug. 31, 2027
Payment to acquire business		$ 12,900,000
Lease percentage		100.00%
Universal Health Services Inc And Catholic Health Initiatives
Related Party Transaction [Line Items]
Number of term renewal options | Time				5
Option to renew lease, notice period prior to termination date of current term				270 days
Renewal period of respective leased facilities at same price after lease terms				270 days
Triple net lease agreement period				20 years
Renewal option term				10 years
Project manager's aggregate fee				$ 750,000
Change in control of trust notice, description				upon 30 days’ notice anytime within 12 months of a change of control of the Trust (UHS also has this right should the JV decline to exercise its purchase right)
Universal Health Services of Delaware Inc
Related Party Transaction [Line Items]
Advisory fee					$ 1,100,000	$ 1,000,000.0	$ 3,300,000	$ 3,100,000
Cost, Product and Service [Extensible List]					Management Service	Management Service	Management Service	Management Service
Average invested real estate assets					$ 641,000,000	$ 594,000,000	$ 623,000,000	$ 587,000,000

[1] Includes bonus rental on UHS acute-care hospital facilities of $1,828 and $1,680 for the three-month periods ended September 30, 2021 and 2020, respectively, and $5,171 and $4,477 for the nine-month periods ended September 30, 2021 and 2020, respectively.