Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Net Operating Revenues, Policy [Abstract]
Value of charity care services at the Company's standard charges included in contractual allowances	$ 126	$ 121	$ 410	$ 350
Estimated cost incurred by Company to provide charity care services	16	$ 15	50	43
Third-Party Reimbursement [Abstract]
Amounts due to third party payors	102		102			$ 144
Amounts due from third party payors	138		138			$ 155
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net			70	314
Goodwill allocated to hospital disposal group held for sale			68	113
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset	621		621
Operating lease liability	$ 634		$ 634
Hospitals Sold or Deemed Held for Sale [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net				225
Write-Off Promissory Note Received as Consideration For the Sale of Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net				29
Adjustment for Carrying Value of Other Long-Lived Assets at Underperforming Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net				$ 60
ASU 2016-02 [Member]
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset					$ 673
Operating lease liability					$ 673