Acquisitions and Divestitures - Additional Information (Detail)		1 Months Ended	3 Months Ended											12 Months Ended
	Dec. 28, 2016 USD ($) Facility	Jan. 31, 2018 Bed	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) Facility	Sep. 30, 2016 USD ($) Bed	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) Facility Bed	Sep. 30, 2015 Hospital Bed	Mar. 31, 2015 Bed	Dec. 31, 2017 USD ($) Hospital Bed	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares
Business Acquisition [Line Items]
Aggregate cash proceeds from divestiture of businesses														$ 0	$ 0	$ 3,000,000
Goodwill recognition description														Goodwill of the facilities acquired during each of the last 3 years is computed, pursuant to the residual method, by deducting the fair value of the acquired assets and liabilities from the total purchase price. The factors that contribute to the recognition of goodwill, which may also influence the purchase price, include the following for each of the acquired facilities: (i) the historical cash flows and income levels; (ii) the reputations in their respective markets; (iii) the nature of the respective operations, and; (iv) the future cash flows and income growth projections.
Net revenues			$ 2,642,787,000	$ 2,541,864,000	$ 2,612,356,000	$ 2,612,858,000	$ 2,475,685,000	$ 2,409,872,000	$ 2,430,855,000	$ 2,449,798,000				$ 10,409,865,000	9,766,210,000	9,043,451,000
Number of hospital facilities | Hospital														3
The Limes
Business Acquisition [Line Items]
Number of beds | Bed														18
Net revenues from discontinued operations														$ 3,000,000
Income before income taxes from discontinued operations														953,000
After-tax income from discontinued operations														770,000
2017 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Acquisition, cash paid														$ 23,000,000
2016 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Acquisition, cash paid															614,000,000
Unaudited pro forma net revenues															9,980,000,000	9,280,000,000
Unaudited pro forma net income attributable to UHS															$ 730,000,000	$ 708,000,000
Unaudited pro forma net income attributable to UHS per diluted share | $ / shares															$ 7.25	$ 7.03
Cambian Adult Services
Business Acquisition [Line Items]
Number of facilities | Facility	79						79
Number of outpatient centers | Facility	2						2
Total purchase price of acquisition	$ 473,000,000
Desert View Hospital
Business Acquisition [Line Items]
Number of beds | Bed								25
Net revenues															$ 12,000,000
2015 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Acquisition, cash paid																$ 534,000,000
Net revenues																30,000,000
Unaudited pro forma net revenues																9,170,000,000	$ 8,350,000,000
Unaudited pro forma net income attributable to UHS																$ 690,000,000	$ 545,000,000
Unaudited pro forma net income attributable to UHS per diluted share | $ / shares																$ 6.85	$ 5.42
Behavioral Health Services
Business Acquisition [Line Items]
Number of beds | Bed													46
Alpha Hospitals Holdings Limited
Business Acquisition [Line Items]
Number of beds | Bed												305
Number of hospital facilities | Hospital												4
Foundations Recovery Network, LLC
Business Acquisition [Line Items]
Number of beds | Bed											322
Number of facilities | Facility											4
Number of outpatient centers | Facility											8
Indefinite lived Tradenames											$ 124,000,000					$ 124,000,000
Subsequent Event | Gulfport Behavioral Health System
Business Acquisition [Line Items]
Number of beds | Bed		109