Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Allowance for Doubtful Accounts, Policy [Abstract]
Number of days from the date of discharge over which all accounts are reserved 100%	365 days
Electronic Health Records Reimbursement, Policy [Abstract]
Electronic health records incentive reimbursement under HITECH	$ 6	$ 18
Electronic Health Records Incentive Reimbursement, Cash Received	10	85
Accounting for the Impairment or Disposal of Long-Lived Assets [Abstract]
Goodwill allocated to hospital disposal group held for sale	192
New Accounting Pronouncements, Policy [Abstract]
Current provision for income taxes	16
Reporting Unit Carrying Amount In Excess Of Estimated Fair Value	800
Electronic Health Records Incentive Reimbursements [Member]
Electronic Health Records Reimbursement, Policy [Abstract]
Deferred Revenue	0	$ 34
Certain Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets [Abstract]
Long-lived assets at certain of the hospitals intended to sell	$ 250