Relationship with Universal Health Realty Income Trust and Related Party Transactions - Additional Information (Detail)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) Hospital Facility	Sep. 30, 2016 USD ($) Hospital	Dec. 31, 2013	Sep. 30, 2017 USD ($) Hospital Facility	Sep. 30, 2016 USD ($) Hospital	Dec. 31, 2016 USD ($)
Chief Executive Officer
Related Party Transaction [Line Items]
Estimated payments to acquire life insurance policies				$ 28,000,000
Payments to acquire life insurance policies				1,200,000	$ 1,300,000
Chief Executive Officer | Trust Owned by CEO
Related Party Transaction [Line Items]
Estimated payments to acquire life insurance policies				9,000,000
Minimum | Chief Executive Officer
Related Party Transaction [Line Items]
Estimated death benefit proceeds				$ 37,000,000
Relationship with Universal Health Realty Income Trust
Related Party Transaction [Line Items]
Trust outstanding shares held, percentage	5.70%			5.70%
Advisory fee earned	$ 900,000	$ 800,000		$ 2,600,000	2,400,000
Pre-tax share of income from the Trust	236,000	250,000		2,300,000	750,000
Carrying value of investment in Trust	8,400,000			8,400,000		$ 7,700,000
Market value of investment in Trust	59,500,000			59,500,000		51,700,000
Rent expense under operating leases	$ 4,000,000	$ 4,000,000		$ 12,000,000	$ 12,000,000
Number of hospital facilities | Hospital	3	3		3	3
Number of free-standing emergency departments to be acquired | Facility	2			2
Lease renewal period, years				5 years
Notice period on renewal of lease				90 days
Period of rights of refusal to leased facilities				180 days
Relationship with Universal Health Realty Income Trust | Minimum
Related Party Transaction [Line Items]
Non-controlling ownership interests by subsidiaries	95.00%			95.00%
Lease initial terms				13 years
Relationship with Universal Health Realty Income Trust | Maximum
Related Party Transaction [Line Items]
Non-controlling ownership interests by subsidiaries	100.00%			100.00%
Lease initial terms				15 years
Premier, Inc. | Group Purchasing Organization Agreement | Restricted Stock
Related Party Transaction [Line Items]
Shares vesting period			7 years
Shares vesting period start year			2014
Shares vesting period end year			2020
Market value of retained vested shares				$ 24,000,000		$ 23,000,000