Basis of Presentation and Significant Accounting Policies (Schedule of Net Operating Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 3,376.0	$ 3,689.0
Medicare [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	889.0	1,033.0
Medicaid [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	428.0	459.0
Managed Care And Other Third Party Payors [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	2,025.0	2,117.0
Self-Pay [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Net operating revenues	$ 34.0	$ 80.0