Basis of Presentation and Significant Accounting Policies (Schedule of Operating Revenue, Net of Contractual Allowances and Discounts (But Before the Provision for Bad Debts)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Operating revenues (net of contractual allowances and discounts)	$ 4,900	$ 3,752
Medicare [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Operating revenues (net of contractual allowances and discounts)	1,298	978
Medicaid [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Operating revenues (net of contractual allowances and discounts)	459	326
Managed Care And Other Third Party Payors [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Operating revenues (net of contractual allowances and discounts)	2,430	1,948
Self-Pay [Member]
Health Care Organization, Receivable and Revenue Disclosures [Line Items]
Operating revenues (net of contractual allowances and discounts)	$ 713	$ 500