Income Taxes (Income Tax Contingency and Taxes Paid Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	11.50%	8.90%	4.90%	7.60%
Effective Income Tax Rate, Continuing Operations, Including Net Income from Noncontrolling Interests	10.30%	8.80%	4.40%	7.30%
Current provision for income taxes			$ 16
Cash Paid for Income Taxes, Net of Refunds Received [Abstract]
Cash paid for income taxes (refunds received), net	$ 5	$ 4	6	$ 4
Certain Hospitals [Member]
Income Tax Contingency [Abstract]
Impairment of long-lived assets held for sale			$ 330