Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jan. 01, 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	$ 5		$ 54	$ 54	$ 135
Electronic Health Records Incentive Reimbursement, Cash Received	7		7	116	71
Reclassification of debt issuance costs						$ 266
Accounting for the Impairment or Disposal of Long-Lived Assets [Abstract]
Write-down of long-lived assets	13	$ 239
Long-lived assets at certain of the hospitals intended to sell		169
Impairment of Long-Lived Assets Held-for-use		$ 70		1,695
Electronic Health Records Incentive Reimbursements [Member]
Electronic Health Records Reimbursement, Policy [Abstract]
Deferred Revenue	$ 0		$ 2	$ 0	$ 2