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, 2018 USD ($) Hospital Facility	Jun. 30, 2018	Sep. 30, 2017 USD ($) Hospital	Dec. 31, 2013	Sep. 30, 2018 USD ($) Hospital Facility	Sep. 30, 2017 USD ($) Hospital	Dec. 31, 2017 USD ($)
Related Party Transaction [Line Items]
Net revenues	$ 2,648,913,000		$ 2,541,864,000		$ 8,017,782,000	$ 7,767,078,000
Chief Executive Officer
Related Party Transaction [Line Items]
Estimated payments to acquire life insurance policies					28,000,000
Payments to acquire life insurance policies, net					1,100,000	1,200,000
Chief Executive Officer | Trust Owned by CEO
Related Party Transaction [Line Items]
Estimated payments to acquire life insurance policies					$ 9,000,000
McAllen Medical Center
Related Party Transaction [Line Items]
Lease renewal option, exercised		5 years
End of lease term		2026-12			2026-12
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%
Pre-tax share of income from the Trust	$ 260,000		236,000		$ 1,100,000	2,300,000
Carrying value of investment in Trust	7,800,000				7,800,000		$ 8,200,000
Market value of investment in Trust	58,600,000				$ 58,600,000		59,200,000
Lease renewal period, years					5 years
Rent expense under operating leases	$ 4,000,000		$ 4,000,000		$ 12,000,000	$ 12,000,000
Notice period on renewal of lease					90 days
Period of rights of refusal to leased facilities					180 days
Number of hospital facilities | Hospital	3		3		3	3
Number of free-standing emergency departments to be acquired | Facility	2				2
Relationship with Universal Health Realty Income Trust | Minimum
Related Party Transaction [Line Items]
Lease initial terms	13 years				13 years
Non-controlling ownership interests by subsidiaries	95.00%				95.00%
Relationship with Universal Health Realty Income Trust | Maximum
Related Party Transaction [Line Items]
Lease initial terms	15 years				15 years
Non-controlling ownership interests by subsidiaries	100.00%				100.00%
Relationship with Universal Health Realty Income Trust | Advisory Fee
Related Party Transaction [Line Items]
Net revenues	$ 1,000,000		$ 900,000		$ 2,800,000	$ 2,600,000
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					51,000,000		$ 33,000,000
Premier, Inc. | Other (Income) Expense, Net | ASU 2016-01
Related Party Transaction [Line Items]
Unrealized gain					$ 19,000,000