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, 2019 USD ($) Facility SquareFoot Bed Lease	Sep. 30, 2018 USD ($)	Dec. 31, 2013	Sep. 30, 2019 USD ($) Hospital Facility	Sep. 30, 2018 USD ($) Hospital	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Net revenues	$ 2,822,453,000	$ 2,648,913,000		$ 8,482,012,000	$ 8,017,782,000
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
Chief Executive Officer | Scenario Forecast
Related Party Transaction [Line Items]
Payments to acquire life insurance policies, net						$ 1,100,000
Chief Executive Officer | Trust Owned by CEO
Related Party Transaction [Line Items]
Estimated payments to acquire life insurance policies				$ 9,000,000
Joint Venture Agreement
Related Party Transaction [Line Items]
Lease initial terms	20 years			20 years
Lease renewal period, years	10 years
Number of beds | Bed	108
Number of triple net lease | Lease	5
Number of square foot to be constructed | SquareFoot	80,000
Expected aggregate fee	$ 750,000
Estimated project cost	37,500,000
Estimated initial annual rent	$ 2,700,000
Expected project to begin and be completed year	2020
Minimum
Related Party Transaction [Line Items]
Lease initial terms	5 years			5 years
Minimum | Chief Executive Officer
Related Party Transaction [Line Items]
Estimated death benefit proceeds				$ 37,000,000
Maximum
Related Party Transaction [Line Items]
Lease initial terms	10 years			10 years
Relationship with Universal Health Realty Income Trust
Related Party Transaction [Line Items]
Trust outstanding shares held, percentage	5.70%			5.70%
Percentage of annual incentive fee				20.00%
Percentage of advisory fee on average invested real estate assets				0.70%	0.70%		0.70%	0.70%	0.70%
Pre-tax share of income from the Trust	$ 300,000	260,000		$ 700,000	$ 1,100,000
Dividends received from the Trust	536,000	528,000		1,600,000	1,600,000
Carrying value of investment in Trust	6,600,000			6,600,000			$ 7,500,000
Market value of investment in Trust	$ 81,000,000.0			$ 81,000,000.0			48,300,000
Lease initial terms	10 years			10 years
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
Number of free-standing emergency departments to be acquired | Facility	2			2
Percentage of master lease rentable square feet				50.00%
Annual Minimum Rent				$ 644,000
Relationship with Universal Health Realty Income Trust | Texoma Medical Center
Related Party Transaction [Line Items]
Number of square feet to be constructed | SquareFoot	75,000
Relationship with Universal Health Realty Income Trust | Minimum
Related Party Transaction [Line Items]
Lease initial terms	13 years			13 years
Relationship with Universal Health Realty Income Trust | Minimum | Limited Liability Companies
Related Party Transaction [Line Items]
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
Relationship with Universal Health Realty Income Trust | Maximum | Limited Liability Companies
Related Party Transaction [Line Items]
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	$ 1,000,000.0	$ 1,000,000.0		$ 3,000,000.0	$ 2,800,000
Premier, Inc. | Other (Income) Expense, Net | ASU 2016-01
Related Party Transaction [Line Items]
Unrealized gain				13,000,000
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				$ 43,000,000			$ 56,000,000