Commitments and Contingencies - Additional Information (Detail) £ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017 GBP (£)	Dec. 31, 2011 USD ($) Hospital	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jan. 31, 2017 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability, current			$ 48,000,000			$ 48,000,000
Compensation liability claims			65,000,000			67,000,000
Compensation and related benefits			33,000,000			33,000,000
Accounts receivable, net			1,447,802,000			1,439,553,000
Letters of Credit and Surety Bonds
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet contingent obligation			122,000,000
Self Insurance Programs | Letters of Credit and Surety Bonds
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet contingent obligation			114,000,000
Other Debt Guarantees | Letters of Credit and Surety Bonds
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet contingent obligation			8,000,000
Location 1
Commitments and Contingencies Disclosure [Line Items]
Minimum Insurance Deductible			50,000
Location 2
Commitments and Contingencies Disclosure [Line Items]
Minimum Insurance Deductible			250,000
Illinois
Commitments and Contingencies Disclosure [Line Items]
Accounts receivable, net			45,000,000			38,000,000
Accounts receivable net greater than sixty days Past due			25,000,000			25,000,000
Flood | Location 1
Commitments and Contingencies Disclosure [Line Items]
Maximum insurance deductible			500,000
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
Percentage of insurance deductible			5.00%
Maximum | Earthquake | LAS VEGAS, NEVADA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses			$ 500,000,000
Maximum | Earthquake | CALIFORNIA
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses			130,000,000
Maximum | Earthquake | UNITED STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses			100,000,000
Maximum | Earthquake | PUERTO RICO
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses			40,000,000
Maximum | Earthquake | OTHER STATES
Commitments and Contingencies Disclosure [Line Items]
Commercial property insurance policies covering catastrophic losses			$ 250,000,000
Minimum | Wind Storms
Commitments and Contingencies Disclosure [Line Items]
Percentage of insurance deductible			3.00%
General and Professional Liability
Commitments and Contingencies Disclosure [Line Items]
Self-insured for professional and general liability			$ 206,000,000			207,000,000
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%
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	$ 250,000,000	$ 250,000,000	$ 200,000,000
Liability for claims paid under commercially insured coverage			$ 50,000,000
Department of Human Services
Commitments and Contingencies Disclosure [Line Items]
Repayment of legal settlement amount on demand		$ 4,000,000
Department of Human Services | Pennsylvania
Commitments and Contingencies Disclosure [Line Items]
Number of behavioral health care hospitals | Hospital		7