Acquisitions and Divestitures (Acquisitions Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2018 item
Business Acquisition [Line Items]
Business combination acquisition related costs	$ 1	$ 1
Number of hospitals acquired | item	0		0
Physician Practices Clinics and Other Ancillary Businesses [Member]
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, purchase price	$ 4
Purchase price allocation, property and equipment	2
Business acquisition, purchase price allocation, intangible assets, other than goodwill	$ 2