Income Taxes (Income Tax Contingency and Taxes Paid Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Contingency [Abstract]
Unrecognized benefit that would affect the effective tax rate	$ 9		$ 9
Amount of interest and penalties included in liabilities for uncertain tax positions	$ 3		$ 3
Effective Income Tax Rate, Continuing Operations	40.10%	34.90%	16.30%	9.00%
Effective Income Tax Rate, Continuing Operations, Including Net Income from Noncontrolling Interests	35.30%	27.40%	14.50%	8.60%
Current provision for income taxes			$ 16
Cash Paid for Income Taxes, Net of Refunds Received [Abstract]
Cash paid for income taxes (refunds received), net	$ 1	$ 2	5	$ 6
Certain Hospitals [Member]
Income Tax Contingency [Abstract]
Impairment of long-lived assets held for sale			$ 363