Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	$ 142	$ 115	$ 284	$ 229
Estimated cost incurred by Company to provide charity care services	18	$ 14	33	28
Third-Party Reimbursement [Abstract]
Amounts due to third party payors	129		129			$ 144
Amounts due from third party payors	136		136			$ 155
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net			71	202
Goodwill allocated to hospital disposal group held for sale			68	$ 77
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset	603		603
Operating lease liability	$ 612		$ 612
ASU 2016-02 [Member]
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset					$ 673
Operating lease liability					$ 673