Acquisitions and Divestitures (Schedule of Net Operating Revenues and Loss and Assets and Liabilities Classified as Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Acquisitions And Divestitures [Abstract]
Net operating revenues	$ 19	$ 24	$ 64	$ 76
Loss from operations of entities sold or held for sale before income taxes	(2)	(3)	(6)	(6)
Impairment of hospitals sold or held for sale	(2)		(9)	(2)
Loss on sale, net			(1)
Loss from discontinued operations, before taxes	(4)	(3)	(16)	(8)
Income tax benefit	(2)	(1)	(6)	(3)
Loss from discontinued operations, net of taxes	$ (2)	$ (2)	$ (10)	$ (5)