Basis of Presentation and Significant Accounting Policies - Additional Information (Details)					1 Months Ended	10 Months Ended	12 Months Ended
	Oct. 27, 2020 Item	Sep. 30, 2020 USD ($)	Jul. 01, 2020 Item	Jan. 01, 2020 Item	Apr. 30, 2020 USD ($)	Oct. 27, 2020 USD ($)	Dec. 31, 2021 USD ($) Item State	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Description [Abstract]
Number of hospitals owned and leased by the Company | Item							83
Number of stand alone rehabilitation or psychiatric hospitals | Item							2
Number of licensed beds | Item							13,289
Number of states in which entity operates | State							16
Cost of Revenue, Policy [Abstract]
Corporate Office Costs							$ 222,000,000	$ 190,000,000	$ 184,000,000
Stock-based compensation expense							25,000,000	13,000,000	10,000,000
Marketable Securities, Policy [Abstract]
Net change in fair value of available-for-sale debt securities, net of tax							(5,000,000)	4,000,000	4,000,000
Property and Equipment, Policy [Abstract]
Construction in Progress, Gross							225,000,000	194,000,000
Interest Costs Capitalized							13,000,000	15,000,000	20,000,000
Purchases of property and equipment and internal-use software accrued in accounts payable							105,000,000	100,000,000
Goodwill, Policy [Abstract]
Impairment of goodwill							0	0	0
Third Party Reimbursement [Abstract]
Amounts due to third party payors							118,000,000	98,000,000
Amounts due from third party payors							114,000,000	136,000,000
Net Operating Revenues, Policy [Abstract]
Charity care services charges excluded from net operating revenues							1,100,000,000	1,000,000,000.0	540,000,000
Value of charity care services at the Company's standard charges included in contractual allowances							123,000,000	122,000,000	66,000,000
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances							2,062,000,000	1,927,000,000
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business							24,000,000	(48,000,000)
Goodwill allocated to hospital disposal group held for sale							5,000,000	110,000,000
Impairment of long-lived assets sold							29,000,000
Divestiture related expenses							$ 3,000,000
New Accounting Pronouncements, Policy [Abstract]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]							true
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]							true
CARES Act
Medicare Accelerated Payments [Abstract]
Medicare accelerated payments received under the Cares Act					$ 1,200,000,000
Medicare accelerated payments, recouped subject to the aforementioned repayment terms							$ 1,100,000,000	77,000,000
CARES Act | Paycheck Protection Program, Health Care Enhancement Act And the American Rescue Plan Act of 2021
COVID-19 Pandemic [Abstract]
Percentage of maximum accelerated payment							100.00%
Medicare accelerated and advance payment program period							6 months
Public Health and Social Services Emergency Fund (the "PHSSEF") | CARES Act | Paycheck Protection Program, Health Care Enhancement Act And the American Rescue Plan Act of 2021
COVID-19 Pandemic [Abstract]
CARES Act and PPPHCE Act of 2020 Aid, amount							$ 186,000,000,000
Public Health and Social Services Emergency Fund (the "PHSSEF") | CARES Act | Paycheck Protection Program and Health Care Enhancement Act
CARES Act and PPPHCE Act Funds [Abstract]
Payments through the PHSSEF and various state and local programs							763,000,000	705,000,000
Public Health and Social Services Emergency Fund (the "PHSSEF") | CARES Act | Paycheck Protection Program and Health Care Enhancement Act | Accrued Liabilities - Other
CARES Act and PPPHCE Act Funds [Abstract]
Payments through the PHSSEF and various state and local programs								14,000,000
Public Health and Social Services Emergency Fund (the "PHSSEF") | CARES Act | Paycheck Protection Program and Health Care Enhancement Act | Operating Costs and Expenses
CARES Act and PPPHCE Act Funds [Abstract]
Payments through the PHSSEF and various state and local programs							148,000,000	601,000,000
Hospitals Closed
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business		$ (3,000,000)
Shared Service Center
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business								(1,000,000)
Hospitals Sold or Deemed Held for Sale
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business						$ 89,000,000	8,000,000	(59,000,000)
Number of hospitals sold | Item	2		1	3
Adjustment for Carrying Value of Other Long-Lived Assets at Underperforming Hospitals
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets held for sale								74,000,000
Medicare
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances							$ 211,000,000	$ 232,000,000
Accounts receivable net of contractual allowances, percent							5.00%	6.00%
Physician Recruitment Contracts
Other Assets, Policy [Abstract]
Term of Physician Recruitment Contract							3 years
Physician Income Guarantees, Policy [Abstract]
Physicians recruitment agreement period							1 year
Term of Physician Recruitment Contract							3 years
Finite-lived intangible assets, net							$ 13,000,000		$ 16,000,000
Capitalized Internal Use Software, Significant System Conversions
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life							3 years
Capitalized Internal Use Software Except Significant System Conversions
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life							3 years
Maximum
Physician Income Guarantees, Policy [Abstract]
Finite-lived intangible assets, net							$ 1,000,000	$ 1,000,000
Land Improvements | Minimum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							3 years
Land Improvements | Maximum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							20 years
Building and Building Improvements | Minimum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							5 years
Building and Building Improvements | Maximum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							40 years
Equipment and Fixtures | Minimum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							3 years
Equipment and Fixtures | Maximum
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life							18 years
Certain Facility
Property and Equipment, Policy [Abstract]
Non-cash investing activity through capital leases							$ 166,000,000
Geographic Concentration Risk | Indiana | Sales Revenue, Net
Business Description [Abstract]
Concentration Risk, Percentage							16.40%	15.00%	13.70%
Geographic Concentration Risk | Florida | Sales Revenue, Net
Business Description [Abstract]
Concentration Risk, Percentage							12.20%	13.00%	14.30%
Geographic Concentration Risk | Texas | Sales Revenue, Net
Business Description [Abstract]
Concentration Risk, Percentage							11.00%	12.20%	12.20%
Geographic Concentration Risk | Alabama | Sales Revenue, Net
Business Description [Abstract]
Concentration Risk, Percentage							13.00%	12.10%	10.60%