Business and Summary of Significant Accounting Policies - Additional Information (Detail) shares in Millions		3 Months Ended									12 Months Ended
	Oct. 01, 2020 USD ($)	Dec. 31, 2020 USD ($) Facility	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2013	Dec. 31, 2020 USD ($) Hospital Facility shares	Dec. 31, 2019 USD ($) Hospital shares	Dec. 31, 2018 USD ($) Hospital Facility shares	Dec. 31, 2015 USD ($)
Summary Of Business And Significant Accounting Policies [Line Items]
Effect of change on after-tax net income		$ 307,734,000	$ 244,092,000	$ 256,504,000	$ 144,460,000	$ 248,010,000	$ 100,870,000	$ 241,265,000	$ 237,398,000		$ 952,790,000	$ 827,543,000	$ 797,883,000
Number of hospital facilities | Hospital											3
Capitalized interest											$ 4,300,000	3,400,000	2,300,000
Depreciation expense											478,800,000	455,600,000	410,000,000.0
Impairment of goodwill or indefinite-lived intangible assets	$ 0											0	0
Impairment of other and intangible assets	0
Provision for asset impairment											0	97,631,000	$ 49,310,000
Intangible assets net		$ 82,586,000				83,657,000					$ 82,586,000	$ 83,657,000
Number of inpatient facilities | Facility													4
Number of outpatient facilities | Facility													12
Behavioral health care facilities with outside owners holding non-controlling minority interest | Facility		3									3
Redeemable non-controlling interest balances		$ 5,000,000									$ 5,000,000
Non-controlling interest balances		85,000,000									85,000,000
Cash flow hedges		0									$ 0
Anti-dilutive weighted average stock options excluded from computation of earnings per share | shares											6.4	5.5	7.9
Revenues		3,086,935,000	$ 2,912,541,000	$ 2,729,754,000	$ 2,829,667,000	2,896,247,000	$ 2,822,453,000	$ 2,855,168,000	$ 2,804,391,000		$ 11,558,897,000	$ 11,378,259,000	$ 10,772,278,000
CARES Act and other Governmental grants and Medicare accelerated payments received		1,112,000,000									1,112,000,000
Revenues from grants											413,000,000
Deferred revenues from grants		4,000,000									4,000,000
Medicare accelerated payments received	323,000,000
Medicare accelerated payments and deferred CARES Act and other grants	372,000,000	376,151,000				0					376,151,000	0
Public Health and Social Services Emergency Fund
Summary Of Business And Significant Accounting Policies [Line Items]
Governmental grants received by CARES Act		417,000,000									417,000,000
Medicare Accelerated and Advance Payment Program
Summary Of Business And Significant Accounting Policies [Line Items]
Medicare accelerated payments received	$ 695,000,000										$ 695,000,000
Repayment period of Medicare accelerated payments received											beginning in the second quarter of 2021 through the third quarter of 2022
Tradename
Summary Of Business And Significant Accounting Policies [Line Items]
Intangible assets net													75,000,000	$ 124,000,000
Foundations
Summary Of Business And Significant Accounting Policies [Line Items]
Provision for asset impairment												98,000,000	$ 49,000,000
Impairment provision for tradename intangible asset												75,000,000
Impairment charges for real property assets												23,000,000
Commercial Insurance Subsidiary
Summary Of Business And Significant Accounting Policies [Line Items]
Statutorily required capital reserves		73,000,000				62,000,000					$ 73,000,000	$ 62,000,000
Universal Health Realty Income Trust
Summary Of Business And Significant Accounting Policies [Line Items]
Number of hospital facilities | Hospital											3	3	3
Investments		5,000,000				6,000,000					$ 5,000,000	$ 6,000,000
Premier, Inc.
Summary Of Business And Significant Accounting Policies [Line Items]
Investments		$ 78,000,000				$ 70,000,000					78,000,000	70,000,000
Premier, Inc. | Group Purchasing Organization Agreement | Restricted Stock
Summary Of Business And Significant Accounting Policies [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											78,000,000	70,000,000
Unrealized gain (loss)											8,000,000
Additional vested shares, value											12,000,000	12,000,000
Acute Care Hospital Services
Summary Of Business And Significant Accounting Policies [Line Items]
Revenues											$ 6,337,304,000	6,164,560,000	$ 5,719,905,000
Acute Care Hospital Services | Las Vegas, Nevada
Summary Of Business And Significant Accounting Policies [Line Items]
Number of hospital facilities | Hospital											6
Acute Care Facility | Washington, District of Columbia | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		20.00%									20.00%
Acute Care Facility | Texas | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		11.00%									11.00%
Acute Care Facility | Nevada | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		5.00%									5.00%
Behavioral Health Care Facility | Pennsylvania | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		20.00%									20.00%
Behavioral Health Care Facility | Ohio | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		30.00%									30.00%
Behavioral Health Care Facility | Washington | Outside Owners
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners		20.00%									20.00%
State Medicaid programs
Summary Of Business And Significant Accounting Policies [Line Items]
Revenue offset amount											$ 185,000,000	194,000,000	179,000,000
Net aggregate benefit											303,000,000	225,000,000	208,000,000
Net revenues											$ 73,000,000	$ 78,000,000	$ 64,000,000
Net Revenue | Las Vegas, Nevada | Geographic Concentration Risk
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of revenue											15.00%	16.00%	15.00%
Minimum
Summary Of Business And Significant Accounting Policies [Line Items]
Patients treated at hospitals for non elective services gross income federal poverty guidelines											200.00%
Minimum | Building and Building Improvements
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives											20 years
Minimum | Equipment
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives											3 years
Maximum
Summary Of Business And Significant Accounting Policies [Line Items]
Patients treated at hospitals for non elective services gross income federal poverty guidelines											400.00%
Maximum | Building and Building Improvements
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives											40 years
Maximum | Equipment
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives											15 years
Medicare
Summary Of Business And Significant Accounting Policies [Line Items]
Revenues											$ 1,690,591,000	$ 1,889,245,000	$ 1,875,875,000
Medicare | Acute Care Hospital Services
Summary Of Business And Significant Accounting Policies [Line Items]
Revenues											1,242,268,000	1,336,200,000	1,296,152,000
Health Care | State Medicaid programs
Summary Of Business And Significant Accounting Policies [Line Items]
Revenues											488,000,000	$ 419,000,000	$ 387,000,000
ASU 2014-09 | Revision of Prior Period Change in Accounting Principle Adjustment
Summary Of Business And Significant Accounting Policies [Line Items]
Effect of change on after-tax net income											$ 1,000,000
ASU 2014-09 | Medicare
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of estimated net revenue adjustment											1.00%	1.00%	1.00%
ASU 2016-01 | Premier, Inc. | Other (Income) Expense, Net
Summary Of Business And Significant Accounting Policies [Line Items]
Unrealized gain (loss)											$ (4,000,000)	$ (4,000,000)
Payments of cash dividends											$ 848,000