Business and Summary of Significant Accounting Policies - Additional Information (Detail)		1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 01, 2017 USD ($)	May 31, 2016 USD ($) Hospital	Dec. 31, 2013	Dec. 31, 2017 USD ($) Hospital Facility shares	Dec. 31, 2016 USD ($) Hospital shares	Dec. 31, 2015 USD ($) Hospital shares
Summary Of Business And Significant Accounting Policies [Line Items]
Establishment of partial reserve in the allowance for doubtful accounts for self-pay balances outstanding from the date of discharge, in days				90 days
Establishment of fully reserve for self-pay balances outstanding from the date of discharge, in days				90 days
Establishment of fully reserve in the allowance for doubtful accounts for third party liability accounts from the date of discharge, in days				180 days
Patients treated at hospitals for non elective services gross income less than federal poverty guidelines				400.00%
Allowance for doubtful accounts				$ 480,000,000	$ 410,000,000
Provision for doubtful accounts				869,077,000	741,578,000	$ 741,273,000
Accounts receivable, net				$ 1,500,898,000	1,439,553,000
Number of hospital facilities | Hospital				3
Capitalized interest				$ 1,000,000	1,900,000	304,000
Depreciation expense				388,400,000	350,800,000	337,500,000
Impairment of goodwill or indefinite-lived intangible assets	$ 0				0	$ 0
Amount of estimated future payments related to physician-related contractual commitments				2,000,000	$ 2,000,000
Amount of potential future financial obligations				$ 2,000,000
Behavioral health care facilities with outside owners holding non-controlling minority interest | Facility				2
Redeemable non-controlling interest balances				$ 7,000,000
Non-controlling interest balances				$ 62,000,000
Anti-dilutive weighted average stock options excluded from computation of earnings per share | shares				6,200,000	2,200,000	765,000
Revenue from Medicaid programs				$ 11,278,942,000	$ 10,507,788,000	$ 9,784,724,000
State Medicaid programs
Summary Of Business And Significant Accounting Policies [Line Items]
Revenue from Medicaid programs				357,000,000	327,000,000	307,000,000
Revenue offset amount				171,000,000	166,000,000	137,000,000
Net aggregate benefit				186,000,000	161,000,000	170,000,000
Net revenues				55,000,000	$ 53,000,000	$ 46,000,000
Commercial Insurance Subsidiary
Summary Of Business And Significant Accounting Policies [Line Items]
Statutorily required capital reserves				$ 110,000,000
Universal Health Realty Income Trust
Summary Of Business And Significant Accounting Policies [Line Items]
Number of hospital facilities | Hospital				3	3	3
Investments				$ 8,000,000
Premier, Inc.
Summary Of Business And Significant Accounting Policies [Line Items]
Investments				33,000,000
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				$ 33,000,000	$ 23,000,000
Building and Building Improvements | Minimum
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives, maximum years				20 years
Building and Building Improvements | Maximum
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives, maximum years				40 years
Equipment | Minimum
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives, maximum years				3 years
Equipment | Maximum
Summary Of Business And Significant Accounting Policies [Line Items]
Property and equipment, useful lives, maximum years				15 years
Acute Care Hospitals
Summary Of Business And Significant Accounting Policies [Line Items]
Provision for doubtful accounts				$ 756,000,000	$ 628,000,000	$ 631,000,000
Medicare And Medicaid | Net Revenue | Customer Concentration Risk
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of revenue				30.00%	32.00%	34.00%
Care Entities | Net Revenue
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of revenue				56.00%	56.00%	54.00%
Illinois
Summary Of Business And Significant Accounting Policies [Line Items]
Accounts receivable, net				$ 25,000,000	$ 38,000,000
Accounts receivable net greater than sixty days Past due				$ 8,000,000	$ 25,000,000
Las Vegas, Nevada | Acute Care Hospital Services
Summary Of Business And Significant Accounting Policies [Line Items]
Number of hospital facilities | Hospital		6		6
Acquisition, cash paid		$ 445,000,000
Purchase price of minority ownership interests		418,000,000
Return of reserve capital to purchase of minority ownership interests		$ 27,000,000
Las Vegas, Nevada | Acute Care Hospital Services | Minimum
Summary Of Business And Significant Accounting Policies [Line Items]
Ownership interests purchased		26.10%
Las Vegas, Nevada | Acute Care Hospital Services | Maximum
Summary Of Business And Significant Accounting Policies [Line Items]
Ownership interests purchased		27.50%
Las Vegas, Nevada | Net Revenue | Geographic Concentration Risk
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of revenue				15.00%	14.00%	13.00%
Washington, District of Columbia | Acute Care Facilities
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners				20.00%
Texas | Acute Care Facilities
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners				11.00%
Pennsylvania | Behavioral Health Services
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners				20.00%
Ohio | Behavioral Health Services
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners				30.00%
Nevada | Acute Care Facilities
Summary Of Business And Significant Accounting Policies [Line Items]
Percentage of non-controlling, minority ownership interests held by outside owners				5.00%