Basis of Presentation and Significant Accounting Policies - Additional Information (Details)		1 Months Ended	3 Months Ended		11 Months Ended	12 Months Ended
	Jan. 01, 2020 Item	Apr. 30, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Cost of Revenue, Policy [Abstract]
Corporate office costs			$ 60,000,000	$ 37,000,000
Third Party Reimbursement [Abstract]
Amounts due to third party payors			102,000,000		$ 102,000,000	$ 98,000,000
Amounts due from third party payors			123,000,000		123,000,000	136,000,000
Net Operating Revenues, Policy [Abstract]
Charity care services charges excluded from net operating revenues			229,000,000	166,000,000
Value of charity care services at the Company's standard charges included in contractual allowances			26,000,000	19,000,000
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business			(21,000,000)	(45,000,000)
Impairment of long-lived assets sold			27,000,000
Impairment of long-lived assets held for sale				64,000,000
Divestiture related expenses			2,000,000
Goodwill allocated to facilities disposal group held for sale			5,000,000		5,000,000
CARES Act
Medicare Accelerated Payments [Abstract]
Medicare accelerated payments received under the Cares Act		$ 1,200,000,000	0
CARES Act | Long-term Liability
Medicare Accelerated Payments [Abstract]
Medicare accelerated outstanding estimated amount under cares act			517,000,000		517,000,000
CARES Act | Accrued Liabilities and Other
Medicare Accelerated Payments [Abstract]
Medicare accelerated payments under cares act			546,000,000		546,000,000
CARES Act | Centers for Medicare & Medicaid Services
Medicare Accelerated Payments [Abstract]
Medicare accelerated repayment under cares act			$ 18,000,000			77,000,000
Medicare accelerated percentage of repayment will occur through an automatic recoupment			25.00%
Medicare accelerated percentage of recoupment will increase			50.00%
Medicare accelerated payments interest rate from the date letter was issued			4.00%
CARES Act | Paycheck Protection Program and Health Care Enhancement Act
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 and Health Care Enhancement Act
COVID-19 Pandemic [Abstract]
CARES Act, PPPHCE Act of 2020 Aid, amount, CAA and ARPA			$ 178,000,000,000
CARES Act and PPPHCE Act Funds [Abstract]
Payments through the PHSSEF and various state and local programs					$ 708,000,000	705,000,000
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			82,000,000			$ 601,000,000
Hospitals Sold or Deemed Held for Sale
Accounting for the Impairment or Disposal of Long-Lived Assets
Gain (loss) on disposition of business			$ 8,000,000	$ 19,000,000
Number of hospitals sold | Item	3