Basis of Presentation and Significant Accounting Policies (Schedule of Net Operating Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 3,246	$ 3,451	$ 9,925	$ 10,702
Medicare [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	811	875	2,519	2,852
Medicaid [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	437	469	1,316	1,407
Managed Care And Other Third-Party Payors [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	1,971	2,065	5,991	6,292
Self-Pay [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 27	$ 42	$ 99	$ 151