Basis of Presentation and Significant Accounting Policies - Schedule of Net Operating Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 3,007	$ 2,519	$ 6,020	$ 5,544
Medicare
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	642	607	1,335	1,363
Medicaid
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	420	341	811	748
Managed Care and Other Third Party Payors
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	1,919	1,626	3,835	3,458
Self-Pay
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 26	$ (55)	$ 39	$ (25)