Commitments and Contingencies - Additional Information (Detail) £ in Millions	1 Months Ended	3 Months Ended		6 Months Ended			12 Months Ended					63 Months Ended
	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2019 GBP (£)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($) Hospital	Jun. 30, 2019 USD ($)	Jan. 31, 2017 USD ($)	Jan. 31, 2017 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability, current		$ 42,000,000		$ 42,000,000			$ 42,000,000					$ 42,000,000
Compensation liability claims		74,000,000		74,000,000			72,000,000					74,000,000
Compensation and related benefits		40,000,000		40,000,000			40,000,000					40,000,000
Accounts receivable, net		1,601,352,000		1,601,352,000			1,509,909,000					1,601,352,000
Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Repayment of legal settlement amount on demand								$ 4,000,000	$ 4,000,000	$ 4,000,000	$ 4,000,000
Amount claimed from over payments of legal settlements								7,000,000	7,000,000	$ 4,000,000
Amount claimed from over payments of legal settlements due to change in calculations									2,000,000
DOJ
Commitments and Contingencies Disclosure [Line Items]
Increase in aggregate pre-tax reserve			$ 9,000,000	134,000,000		$ 22,000,000	123,000,000
Pre-tax increase to reserve for civil aspects		11,000,000		11,000,000
DOJ | Subsequent Event
Commitments and Contingencies Disclosure [Line Items]
Definitive settlement and related civil agreements	$ 127,000,000
River Point Behavioral Health
Commitments and Contingencies Disclosure [Line Items]
Amount withheld in contingent Medicare payment suspension												9,000,000
Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Minimum Insurance Deductible		50,000		50,000								50,000
Maximum insurance deductible		250,000		250,000								250,000
Flood
Commitments and Contingencies Disclosure [Line Items]
Maximum insurance deductible		500,000		500,000								500,000
Illinois
Commitments and Contingencies Disclosure [Line Items]
Accounts receivable, net		26,000,000		26,000,000			32,000,000					26,000,000
Accounts receivable net greater than sixty days Past due		12,000,000		12,000,000			18,000,000					12,000,000
Pennsylvania | Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Number of behavioral health care hospitals | Hospital											7
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								$ 1,000,000,000
Percentage of insurance deductible		5.00%		5.00%								5.00%
Maximum | LAS VEGAS, NEVADA | Earthquake
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses		$ 500,000,000		$ 500,000,000								$ 500,000,000
Maximum | CALIFORNIA | Earthquake
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses		130,000,000		130,000,000								130,000,000
Maximum | Faulty Zones of UNITED STATES | Earthquake
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses		100,000,000		100,000,000								100,000,000
Maximum | PUERTO RICO | Earthquake
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses		40,000,000		40,000,000								40,000,000
Maximum | OTHER STATES | Earthquake
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses		$ 250,000,000		$ 250,000,000								$ 250,000,000
Minimum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Percentage of insurance deductible		3.00%		3.00%								3.00%
General and Professional Liability
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability		$ 248,000,000		$ 248,000,000			$ 243,000,000					$ 248,000,000
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%								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								$ 250,000,000	$ 200,000,000						$ 250,000,000	$ 250,000,000
Liability for claims paid under commercially insured coverage		$ 5,000,000		$ 5,000,000								$ 5,000,000
Subsidiaries | General And Professional Liability Insurance Policies | Maximum | Located in U.K.
Commitments and Contingencies Disclosure [Line Items]
Liability for claims paid under commercially insured coverage		$ 8,500,000		$ 8,500,000								$ 8,500,000