Commitments and Contingencies - Additional Information (Detail) £ in Millions	12 Months Ended					45 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 GBP (£)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($) Hospital	Dec. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jan. 31, 2017 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability	$ 298,222,000					$ 298,222,000			$ 274,815,000	$ 271,476,000	$ 259,718,000
Self-insured for professional and general liability, current	54,000,000					54,000,000			48,000,000
Compensation liability claims	70,000,000					70,000,000			67,000,000
Compensation and related benefits	35,000,000					35,000,000			33,000,000
Combined estimated future purchase obligations	315,000,000					315,000,000
Defined benefit pension plan estimated payments through 2089	188,000,000					188,000,000
Other retirement plan liabilities	18,000,000					18,000,000
Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Repayment of legal settlement amount on demand			$ 11,000,000	$ 11,000,000	$ 4,000,000
McAllen Medical Center
Commitments and Contingencies Disclosure [Line Items]
Amount awarded to plaintiff	3,850,000
Total amount of order, including prejudgment interest	9,000,000
DOJ
Commitments and Contingencies Disclosure [Line Items]
Reserve for civil aspects	22,000,000					22,000,000
River Point Behavioral Health
Commitments and Contingencies Disclosure [Line Items]
Amount withheld in contingent medicare payment suspension						10,000,000
Construction Commitment
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	30,000,000					30,000,000
Revenue Cycle Data Processing Services
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	73,000,000					73,000,000
Electronic Health Records And Revenue Cycle Application
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	240,000,000					240,000,000
Estimated Minimum Liabilities For Physician Commitments
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	2,000,000					2,000,000
Related to Certain Equipment
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	206,000,000					206,000,000
Commercial Health Insurer and Self-insured Employee Benefit Plans
Commitments and Contingencies Disclosure [Line Items]
Combined estimated future purchase obligations	86,000,000					86,000,000
Pennsylvania | Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Number of behavioral health care hospitals | Hospital					7
Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Minimum Insurance Deductible	50,000					50,000
Maximum insurance deductible	250,000					250,000
Flood
Commitments and Contingencies Disclosure [Line Items]
Maximum insurance deductible	500,000					500,000
Professional And General Liability
Commitments and Contingencies Disclosure [Line Items]
Increase in professional and general liability self-insurance reserves relating to prior years	15,000,000
Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Property insurance | £		£ 1,290
Maximum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	$ 1,000,000,000					$ 1,000,000,000
Percentage of insurance deductible	5.00%					5.00%
Maximum | Earthquake | LAS VEGAS, NEVADA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	$ 500,000,000					$ 500,000,000
Maximum | Earthquake | CALIFORNIA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	130,000,000					130,000,000
Maximum | Earthquake | PUERTO RICO
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	40,000,000					40,000,000
Maximum | Earthquake | OTHER STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	250,000,000					250,000,000
Maximum | Earthquake | Faulty Zones of UNITED STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses	$ 100,000,000					$ 100,000,000
Minimum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Percentage of insurance deductible	3.00%					3.00%
General and Professional Liability
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability	$ 228,691,000					$ 228,691,000			207,459,000	203,973,000	192,904,000
Subsidiaries | Professional Liability | Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability | £								£ 10
Subsidiaries | Professional Liability | Maximum
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability							$ 5,000,000		10,000,000
Subsidiaries | General Liability | Cygnet Health Care Limited
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability | £								£ 25
Subsidiaries | General Liability | Maximum
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability							$ 3,000,000		3,000,000
Subsidiaries | General And Professional Liability Insurance Policies
Commitments and Contingencies Disclosure [Line Items]
Percentage of liability for claims paid under commercially insured coverage	10.00%					10.00%
Subsidiaries | General And Professional Liability Insurance Policies | Maximum
Commitments and Contingencies Disclosure [Line Items]
Purchased several excess policies through commercial insurance carriers per occurrence			$ 200,000,000						$ 250,000,000	$ 250,000,000	$ 250,000,000
Liability for claims paid under commercially insured coverage	$ 5,000,000					$ 5,000,000