Basis of Presentation and Significant Accounting Policies (Schedule of Net Operating Revenue) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 3,286	$ 3,246	$ 3,302	$ 3,376	$ 3,453	$ 3,451	$ 3,562	$ 3,689	$ 13,210	[1]	$ 14,155	[1]	$ 15,353
Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues									13,210		14,155
Prior to Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues													18,398
Medicare [Member] | Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues									3,331		3,730
Medicare [Member] | Prior to Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues													4,188
Medicaid [Member] | Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues									1,736		1,876
Medicaid [Member] | Prior to Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues													1,900
Managed Care And Other Third Party Payors [Member] | Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues									8,014		8,349
Managed Care And Other Third Party Payors [Member] | Prior to Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues													9,991
Self-Pay [Member] | Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues									$ 129		$ 200
Self-Pay [Member] | Prior to Adoption of ASC 606 [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues													$ 2,319

[1] Total quarterly amounts may not add due to rounding.